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Common Tank Wash Questions

1. Will I need to change my pump?

Watch our video Do I need to change my pump for my new tank wash system? or read on below to find out if you need to change your pump when installing or upgrading to a new cleaning-in-place / tank wash system.

 

Will I need to change my pump? This is a question we get asked a lot and this is the first in a series of FAQs answering common questions about tank cleaning and changing tank cleaning systems. The short answer to whether you will need a new pump for your CIP system is possibly.

 

There are two limiting factors for a pump: the maximum pressure it can deliver and the maximum flow rate it can deliver. And this is what we need to consider when we're looking at changing our tank cleaning systems.

 

Generally speaking, if the newly proposed tank cleaning system is lower in both required pressure and flow rate then the existing pump will be fine and you won't need to change it, if the required or ideal new pressure for the new tank cleaning system is higher or the flow rate is higher, then there will be a possibility that you need to change the pump. But not always, as we'll see.

 

Normally, when moving from a spray ball or to a spinner - so upgrading from a static spray ball to a spinning spray ball - the optimal pressures will be about the same. And so you don't really need to consider whether the pump can operate at high pressure because it won't need to; both these systems run at roughly the same pressure. And when moving from spray balls to spinners, the overall flow rate for the spinner is, in almost all cases - and this is one of the reasons why we make that move - lower than in the spray ball.

 

So generally speaking, if we're moving from spray balls to spinners, the existing pump is going to be fine. If, for whatever reason, you're moving the other way round, so you're downgrading in effect from a spinning spray ball to a static spray ball, then you will need to look at the flow rate of the new spray ball system because if that's higher than the existing pump can deliver, then you probably may need to change your pump to a higher capacity pump.

Things are a little bit more complex when we start to make the move from spinners and spray balls to rotary jet cleaners. Typically, these rotary jet cleaners work most efficiently at pressures above about six bar. And ideally, we want to be normally within the sort of eight to ten bar fluid pressure range. This is quite a lot higher than the two to three bar that is optimal for spinners and spray balls, so we need to make sure that the pump can actually deliver the required pressure. Flow rates again typically will go down when we're moving from spray balls to rotary jet cleaners.

 

So again, we're not too concerned about the flow rate capacity of the pump. Normally, this will be fine, but we are worried about that higher maximum pressure the pump can deliver. If it cannot deliver the required pressure, then obviously you're going to need to upgrade the pump.

 

However, things are slightly more complicated when it comes to looking at things like centrifugal pumps, because centrifugal pumps will deliver variable pressure depending on what the pipe system actually sees. So if we're moving from a spinner running at three bar to a rotary jet cleaner that wants to run at six bar, if the flow rate for the rotary jet cleaner is considerably lower, that centrifugal pump may equalise at a higher pressure and a lower flow rate. So a typical example would be you moving from a spray ball, running at three bar using 250 litres a minute and say the rotary jet cleaner that you're proposing wants to run at six bar at 125 litres a minute then that same pump may well be able to do that. What you need to do is to check the pump curve to see whether it can actually cope with the lower flow rate, higher pressure scenario.


If it can't, then you're going to need to upgrade the pump. If you can, great. But remember, you always need to take into account gravitational and frictional pressure losses as well. So we may need to take into account the pressure right at the pump is going to be different to the one delivered actually at the cleaning head. If we're moving to a high pressure jet cleaning system, you're almost certainly going to need a new pump - high pressure tank cleaning systems need between 50 and two hundred bar. That almost always requires a change of pump and especially a specialist high pressure pump. And you're also going to probably need to upgrade your pipework as well, in all likelihood, to high pressure pipework.

 

So to recap:

- you're not going to need to change your pump if the required pressure and flow rate on the new
tank cleaning system are both lower in the new system than the old system

- you probably won't need to change your pump by moving from spray balls to spinners

- you may well need to upgrade your pump to be able to deliver the higher maximum pressure when upgrading from spinners or spray balls to jet cleaners but you might get away with it if the flow rate is reduced and the pump naturally can settle into that high pressure regime

- you will definitely need to change your pump when moving to a high pressure system and probably your pipework as well.

 

2. How long does it take a CIP system to clean a processing or storage tank?

This is is a key question we get asked an awful lot at the Spray Nozzle People when looking at tank cleaning applications. Watch our video How long does it take to clean a tank?  or keep reading below.

 

So how long does it take to clean a processing or storage vessel? It is a key question and can be one of the most important in terms of operational efficiency. When they're being cleaned, any tanks are not being used for whatever they're normally being used for.
So effectively what we have is operational downtime when the tanks are being cleaned. So the time it takes to clean a tank can actually be the most important thing for many customers, and improving on tank cleaning times is a key thing we get asked to address.

 

So in absolute terms, it's impossible to actually answer the question because each residue and each tank are different. So rather than talking about absolute terms i.e. for this residue, it will take this long to clean this tank, we talk about it in relative terms, i.e. comparing the different time periods different styles of tank cleaners will take. The length of time any tank cleaning or any cleaning operation needs to run depends on four main things:

 

1. Time is one of the four key factors in any cleaning operation, along with 2. mechanical action, 3. chemical action and 4. heat. Each of these factors combine to give an overall cleaning effectiveness. So if we want to reduce one, we need to increase one of the others and vice versa. So when answering the question, how long will it take to clean the tank we actually need to know what the other three factors are. So it's not a simple question. But, we can look at the mechanical action component because this is the key difference between the different styles of tank cleaners.

 

We'll assume for the purpose of this exercise that we will keep the chemical action the same and the heat the same. And we'll just look at the varying mechanical action components of the different styles of tank cleaners.

 

Spray balls have a very, very low mechanical action, and so all other things being equal, they will need longer to clean any tank.
If we increase the mechanical action by upgrading the spray balls to spinners, we improve the mechanical action of the cleaning system and so can reduce the time it takes. Now it's hard to say by how much, but a general rule of thumb we would expect to see the same level of cleaning in about 50 to 75% of the time so a 20 minute clean would be reduced to between ten and 15 minutes. If we decide to upgrade further to a rotary jet cleaners, then the mechanical action is increased even more dramatically and we can see even bigger reductions in time. The same level of cleaning can be delivered in perhaps 25% of the time. So that same 20 minute cleaning for a spray ball will be reduced to perhaps five minutes with a rotary jet cleaner.

 

However, there's one big caveat with this. The jet cleaner must be able to complete its complete cleaning cycle to ensure that the jets reach all areas of the tank. Otherwise, parts of the tank simply won't be cleaned. So there's a hard limit on the time savings that can be achieved i.e. you can't reduce the cleaning time below that overall cycle time. So, with very light residues in small tanks that are cleaned well by a single spray ball in five minutes, you're going to actually struggle to improve the cleaning time even with rotary jet cleaners; most cleaning cycles of most jet cleaners are more than five minutes. You can still improve on overall water consumption by making that upgrade, and the jet cleaner may well do the same job with less water over that five minute period, but from a purely time perspective, improvement is unlikely to be achievable with those kind of light residues in small tanks. However, if the spray ball wash was taking, say, 30 minutes, then it's a completely different story and the rotary jet cleaners will likely produce significant time reductions.

 

So hopefully that gives you some  idea of how to answer the question how long will it take to clean a tank? The absolute answer is it's difficult to give because it's very much dependent on the residue in the tank in question, but the relative answers given here can help you make some sensible decisions when choosing the style of tank cleaning that you want for your CIP system.

 

3. What is the optimal position for a tank cleaning head?

This common question has a surprisingly simple answer, but as we'll see, there are some complexities. As a general rule of thumb we want to position all tank cleaners on the centre line of the tank. Read on or watch our video What is the optimal position for a tank cleaning head?


We are assuming in this part of the discussion that we're talking about common cylindrical tanks. So, in a common cylindrical tank you want to position the tank cleaner on the centre line towards the top about one third of the way down the tank from the top of the tank.

 

This general rule applies for all styles of tank cleaners, and it generally gets the best results. The reason for this is gravity is our friend in tank cleaning. So the lower parts of the tank will naturally receive all of the washed down water that is used in the cleaning operations for the higher part of the tank. 

 

So, one third of the way down on the centreline is the optimal position, but there are some complications. The first thing we need to consider is product line. So if the product line is normally above two thirds of the way up the tank, then it's often advisable to raise the tank cleaner above this line. It may be suboptimal for cleaning, but having the tank cleaning head covered with the product in normal operation can cause more problems. And this depends very much on the product, and in many cases, it's actually fine to have the tank cleaning head submerged but we need to consider that.

 

The next thing to think about is internal obstructions. Central agitators or other tank internals may mean it's actually impossible to have the tank cleaning head on the centre line. Furthermore, these obstructions will cause shadowing and block the path of the tank cleaning fluid, meaning some parts of the tank wall are not cleaned. Now, in this situation, we need to position the tank cleaner away from the centre line because it's not possible to put it on the centre line. Now, if we are only using one tank cleaner and we're not too worried about shadowing, then getting it as close to the centre line as possible is a good idea. So getting as close to that optimal position as possible. Now, if we're going to be using two tank cleaners to overcome the shadowing effects from internals or the central agitators, then having them equidistant from the centre is best practice.

 

Effectively, what you want to consider is dividing the tank into two half cylinders, two virtual tanks if you like, and then have each tank cleaning head positioned optimally for that half cylinder, i.e. the centre line of that half cylinder and each tank cleaning head is now responsible for cleaning half the tank.

 

Now, obviously, there will be large parts of the tank cleaning from each virtual tank that will spill over into the other tank, and that's kind of bonus cleaning. But if we design the system so that each half tank can be cleaned by a single tank cleaner and that's positioned optimally, then that's going to be best practice. 

 

So what about odd shaped and large tanks? Things get a little bit more complicated here when moving away from the standard cylindrical shaped tanks. So some general rules of thumb for any shaped tank - one third of the way down the tank is still a pretty good general rule from the top. And the basic principle we want to have is to have as much of the tank as equidistant from the actual tank cleaning head as possible. Now this is often not possible in odd shaped tanks.

 

So for example, long tanks or cylindrical tanks on their side, this means in order to get equal coverage and equal cleaning, we may want to have a couple of tank cleaners in there at each end of the cylinder.

 

When looking at the maximum cleaning distances of any tank cleaner, we need to consider the worst case scenario, i.e. what's the furthest point that needs to be cleaned by the tank cleaner? Now, for spinners and spray balls, this distance should be the maximum horizontal distance from the cleaning head to the wall.

 

This should be kept below the scrubbing distance indicated on the data sheet. For rotary jet and high pressure cleaners, the best practice is to measure the distance from the cleaning head to the furthest point that needs to be cleaned; in most tanks. This will be the bottom edge of the tank. Now this distance can be calculated using Pythagoras theorem. The distance should be less than the rated effective cleaning jet length on the data sheet. It is sometimes, however, acceptable to use the same basic horizontal distance calculation to the tank wall when sizing and positioning jet cleaners. Typically for lighter residues
this is fine. 

For odd shaped tanks that require multiple tank cleaners, it's best to divide the tank into virtual sub tanks again and then position a tank cleaning head in each of these virtual sub tanks using the same rules as if they were separate tanks and they were only being cleaned by that one tank cleaner. Any of the overspray outside of these virtual tanks into the next adjacent virtual tank is just bonus cleaning. But if you stick to the rule that you're cleaning a virtual tank with one tank cleaner, you're not going to go far wrong.


So these are the principles that we apply when designing tank cleaning systems with regards to optimal positioning of tank cleaning heads. Please do not hesitate to contact us with any questions you may have.

 

4. What's the best way to mount a tank cleaning system?

 

We've selected our tank cleaner for optimal results. And now we need to position it in the tank. We know where we want to put it in the tank for optimal results. So how do we now mount that in the tank? And there are a number of rules, general rules we can apply when considering a suitable mounting system. So first of all, with any mounting systems, careful thought needs to be given to how we're going to remove that tank cleaner from the tank.  Read on or watch our video What's the best way to mount a tank cleaning system

 

Tank cleaners will need to be maintained from time to time, so any such system needs to be easily removeable. So we need to design that into the system. So that's a very important consideration. The second consideration is hygiene. Many tank cleaning systems obviously need to be highly hygienic, particularly in food processing and in the pharmaceutical industry. So we need to ensure that all of the connections that connect the tank cleaner to the mounting system and then connect the fluid supply to the mounting system outside the tank are hygienic connections as well.

 

So we might want to look at things like tri- clamps or something like that to ensure a complete end to end hygienic design. And the third general consideration is how are we going to get the tank cleaner in the optimal position in the tank?

 

How are we going to design the mounting system so that it can actually get the tank cleaner where it goes/where it needs to be?
So by far the most common is top mounting / roof mounting. So this is a simple, centrally mounted down pipe in the roof of the tank that positions the tank cleaner in the ideal position, and this can be fixed to the tank roof via a wall or a tri-clamp connector and the tank clean can be removed through the flange for maintenance. Now, in some cases an angled position pipework may be advisable to get the tank cleaner into the correct optimal position. So if we don't have a suitable opening in the tank roof that's directly on the centreline a slightly kinked pipe that will position the tank cleaner on the centreline may be advisable, but obviously you need to consider how you can get that out again as well. 

 

The other option if roof mounting isn't suitable for whatever reason is side mounting. We can actually come through this wall of the tank on a horizontal pipe and position the tank cleaner in the correct position. Obviously, we need a 90 degree bend at the end of that pipe so the tank cleaner can be positioned in its normal downward facing position and then due to the extended profile of that set up, we're going to need to consider carefully how we're going to get the thing out again so that can be problematic but side mounting is an option. 

 

Now, another option for certain styles of tank cleaners are wall mounted or through-the-wall and this is different to side mounting. Certain styles of tank are designed to actually sit flush with the wall and pop into the tank to perform their tank cleaning operation. These pop-up nozzles are generally secondary tank cleaners and are used to used to hit problem spots that won't be hit by the primary tank cleaner which would typically be positioned at the top of the tank. So wall mounting is an option. What happens with these systems is they're designed to sit very flush with the wall, so it just looks like a normal tank wall there when the tank is being used. And then when the cleaning cycle begins with the tanks empty, the nozzle actually pops through the wall under the fluid pressure and starts to spin or spray, hits its specific target and then pops back again once the fluid pressure has gone off, so that's a nice handy option for those spot cleaning applications.

 

Now looking at bigger tanks, another option is what we call roof mounting. And this is different to the top mounting because what we're talking about here is very large tanks with perhaps concrete roofs that people can walk over so something like a stormwater attenuation tank, for example. And in these situations, what we would typically do is have a down pipe up through a manhole cover and then the whole assembly can be lifted through the roof for maintenance and the important design consideration here is we need to make sure that the weight of the overall down pipe assembly and tank cleaner are below the minimum health and safety minimum weight for a single person lift. Otherwise, you're going to need two people to take the tank cleaner out each time and that can be problematic. So keeping weight down in the design is an important consideration in that instance. 

 

Now for very large open tanks again, like storm attenuation tanks, you can't roof mount them because they don't have a roof. So what do we do?  We can mount these from the side and, typically, what we do is mount them on swing arms. So we'd be using 180 degree downward tank cleaners in these situations because, otherwise, using a 360 one obviously without a roof the fluid is going to be flying all over the place. So you mount them on a swing arm and this swing arm could go maybe two or three metres into the tank. So we're getting some kind of good positioning of the tank cleaner inside the tank.

 

And then when it comes to maintenance, the arm swings back to the side of the tank and the tank cleaner can be removed easily for maintenance. So those are the common options that we provide for our customers when it comes to mounting tank cleaners.

 

We hope you found that guide useful. I hope it gives you some ideas and of course, if you have any further questions, please do get in contact with us.

 

5. At what pressure should we run our tank cleaners?

 

At what pressure should we run our tank cleaners? And is higher pressure more efficient, more effective? Read on or watch our video At what pressure should we run our tank cleaners?

 

Now this is an interesting question that we get asked an awful lot at the Spray Nozzle People when sizing in new or upgrading tank cleaning systems. And there are some counterintuitive and somewhat surprising answers to this question.

 

So let's have a look at each type of tank cleaner in sequence. For spray balls and other static non-moving tank cleaners, the general rule is you really don't want to go much above three bar in fluid pressure and not really anything below one bar.

 

The sweet spot of around two, two and a half bar is about right, but we wouldn't increase any pressure more than that.
Now, this may seem surprising and counterintuitive. Surely, you would think,  if we increase the fluid pressure, then we're going to get more impact and we're going to get a better clean. Well, actually, no, we're not. 

 

Now spray balls actually have very poor nozzles in them - they are effectively a sphere with multiple holes drilled in and those holes act as multiple nozzles. But they're very, very poor nozzles and they're just a hole in a sheet of metal. 

 

The jets that come out of these don't have very good integrity. So as we increase the pressure, increase the velocity of these, they tend to break up and atomise quite easily because it's a poor quality jet coming out of it. So as we increase much beyond that sort of three bar pressure threshold, all we're really doing is atomising the fluid more and we're destroying any extra impact that might have been achieved by the increased pressure.

 

So we're basically wasting energy. So there's no real point  in spraying them much above sort of three bar. For spinning spray balls, rotary nozzles, the situation is actually quite similar. 

 

Anything much above the sort of three bar pressure range, they're going to start spinning faster and faster, and you're going to start flinging that water around really, really quickly and atomising it more. So again, you've got a sweet spot of around two and a half to three bar, maybe a little bit more than that, where you can get the optimal cleaning out of them. Anything much above that you're going to not get any extra impact out of them. And you're also going to increase the wear on these spinners because as they spin faster, they start to wear more easily so you're going to start to run into problems with wear as well. So you want to keep that pressure around about the three bar mark, not much more than that. 

 

Now for rotary jet cleaners the situation is different. These cleaners have specialist nozzles on them that are designed to keep their jets in laminar flow, even at relatively high pressures so we have a coherent jet coming out of these jet cleaners designed to  stay laminar and not break apart and deliver impact to the walls.

 

That's the whole point of these tank cleaners. So they're going to give  good, stable jets at pressures, for most models, up  to about ten bar. Increasing pressure from two to six to ten bar will improve both the jet length and the impact and also improve the overall efficiency of the tank cleaning head.

 

And the reason for that is that they rotate through their cleaning cycle quicker and quicker as we increase pressure and the decrease in the time it takes to complete its cleaning cycle more than offsets the additional flow rate we'd get at the higher pressure. So what we find is the overall liquid used per cleaning cycle on any given tank cleaner actually comes down as we increase pressure and the sweet spot is normally around about that eight to ten bar mark by then and most efficient so they'll use less per cleaning cycle and they'll have an improved cleaning action due to the improved mechanical action of the jets. 

 

Now for high pressure tank cleaning - and this is high pressure tank cleaning jets, we've defined as anything running above sort of 50 bar, and they often run a lot more than that. Again, we have these high integrity nozzles that produce these needle like laminar flow jets, even at very high pressures. But because the pressure is so high and the resulting velocity of those jets is so high, this laminar flow can't be maintained for as long as in the lower pressure 10 bar rotary jet cleaner styles. So we actually find that the effective jet lengths are reduced and this is because they're typically very low flow rate running at very high pressures and so very high speeds and so much beyond a couple of metres from the tank cleaning nozzle and we start to see that atomisation effect come into play again. And so they're not really suitable for very large tanks where we require a jet length of, you know, four or five, six, seven, eight metres.

 

You probably wouldn't use one of these high pressure nozzles in that situation, because even though they've got the higher pressure, the jet lengths just aren't effective at those ranges due to that atomisation effect. Now you can use them on bigger tanks if you can facilitate multiple stage cleans so you effectively move the high pressure cleaner into different parts of the tank so it can clean each bit within that relatively short range of its cleaning jets.  So that can be done as well, and that can be a very efficient way of tank cleaning. But unless you can do that, you wouldn't use them for big tanks. 

 

So to recap, the general rules we have are for spray balls and other static nozzles, you want to keep the pressure around two to three bar for optimum results. Any more than that is normally just a waste.

 

For spinners, the same rules apply so around about that three bar, anything more than about three bar pressure is going to be a waste. For rotary jet cleaners, we improve efficiency as we move up the pressure and the sweet spot on those is normally about eight to ten bar so you are going to be trying to run them at those pressures for optimal results.

 

And for high pressure jet cleaners, run them at the manufacturer's recommended pressures. But bear in mind that because these jets are moving so fast they do tend to atomise a relatively short distance from the jet, so you wouldn't want to be using them where you require a jet length of more than two to three metres or so.

 

So I hope that guide is helpful and that gives you some guidance on what are the optimal pressures for the various different tank cleaners.

 

6. How much does a tank cleaning system cost?

Watch our video How much does a tank cleaning system cost? or read on below to find out the cost of CIP systems such as spray balls, rotary nozzles and rotary jets.

 

What is the difference in price between the different styles of tank cleaning head? Now, obviously, this is an important question to answer. And the short answer is as follows: for standard static spray balls expect to pay anywhere between 50 and £300 per spray ball depending on the size - the bigger the spray ball, the more expensive they are. This assumes a standard 316 stainless base material. You can expect to pay a lot more for hastelloys and, for other specialist materials, the prices obviously go up. 

 

For spinners, so the spinning style spray balls, expect to pay between £150 and up to about £500 per spinner for a decent brand. Now there are a lot of not so decent brands out there, and it's really worth buying a good one that's going to last. In the grand scheme of things a few hundred quid is neither here nor there when compared to the cost of contaminated batches or poor cleaning from a shoddily made spinner. So get it, get a good brand and expect to pay £250 to £500, depending on the size of it.

 

Now, for rotary jet cleaners expect to pay between around £2000 to £3,500 for a decent brand. Again, there are plenty of clones that aren't so decent out there clones of the main brands. With, how shall we say, variable quality.

 

The brands we come across and rate as good brands apart from our own ones, of course, which are manufactured by Dasic Marine here in the UK. The other good brands out there that we consider to be true competitors of ours are manufactured by Alfa Laval, Spraying Sytems, Lechler and GEA.

 

There might be a few I've missed, but you know these are the good, good quality tank cleaners out there, and they're all much of a muchness in terms of price so expect to pay within that sort of £2000 to £3500 price for a rotary jet cleaner. Now, you know, you will see that there are equivalent cloned models from fairly random manufacturers from around the world in about £1000 price range, and probably not a good idea. The quality is probably not going to be there.

 

For high pressure cleaners, expect to pay anywhere between £2000 and about £5000, maybe a little bit more for a decent brand - high pressure cleaners are the ones that are running at sort of 50 bar plus. And again, the same rules apply about buying quality from reputable brands. There are cheaper copies available, but it's not a great idea given the potential cost of failure now. So that's the simple answer to the question of cost.

 

Now, for a slightly more nuanced answer, we need to look at the overall cost of the system. So spinners and spray balls have the advantage of being low pressure systems operating optimally around two to three bar fluid pressure. So this means lower operating costs, low fittings costs, low pipework costs.

 

The downside is they actually have a much higher cost of running because they're not very water efficient; they're very inefficient in terms of water consumption compared to, say, jet cleaners. So the overall lower infrastructure costs and the cost of the hardware itself in many cases, in fact, often is outstripped by the additional cost of water and disposal of that water over the year or two year period. They also take considerably longer to clean tanks than in most situations than rotary jet cleaners.

 

So there's an opportunity cost associated with this longer tank cleaning cycle all the time, all the while the tank being cleaned, it can't be used. So what's the opportunity cost of having a tank inoperable whilst it's being cleaned?

 

What's the cost of an extra two or three hours a week, if that's what the differential between using spray balls and rotary jet cleaners would be? What's that differential cost? And we need to take that into account as well.

 

Now, rotary jet cleaners cost more for the hardware, as we've seen, but they also may need an increase in the pump capacity to accommodate the higher pressures that they want to run at. So that needs to be factored in as well.

 

But as noted above, they are a lot more water efficient than spinners and spray balls. So what we often find is despite the additional cost of the hardware and despite the additional cost of maybe an upgraded pump over the long period, over the course of the year, they actually save an awful lot of money because of efficiency gains. 

 

Now, for high pressure cleaners, we need high pressure pumps and high pressure pipe work because it's a whole different ballgame running something at about ten bar, which is the optimal pressures for standard rotary jet cleaners and if we're then, you know, moving up to 50 or 100 bar we're going to need to change to high pressure pipe work. We're going to certainly need some high pressure pumps and we need to factor in all of the wear and tear and also all of the additional health and safety considerations that go with running it in a high pressure fluid system.

 

So these are all going to increase the overall costs. To balance this large additional infrastructure costs, they will use less fluid than rotary jet cleaners. OK, so you know, they may well be more fluid efficient per cleaning cycle and in fact often they will be so we need to have a balancing consideration between those much larger infrastructure costs and the benefits of having a more water efficient tank cleaning system. So to recap the short answer, static spray balls expect to pay between £50 to £100 for a standard 316 stainless spray ball.

 

For spinners from decent manufacturers expect to pay between about £150 and £500 for the spinner, depending on the size of it. There are a lot of cheap knock offs out there, but avoid those because the cost of failure is so high.

 

Decent rotary jet cleaners from the good manufacturers cost between £2000 and £3500 and then high pressure cleaners are going to be more expensive than that so £2500 to £5,000 for a high pressure cleaner from a decent manufacturer.

 

7. How far does a tank cleaner clean?

 

Watch our video How far will my tank cleaner clean? or read on below to find out more.

 

How far will my tank cleaner clean? This is a question we get asked a lot at The Spray Nozzle People when sizing up new or upgrading tank cleaning systems - at what distance from the tank cleaning head will it still be effective? Obviously, this is clearly a very important question to understand and answer. 

 

On tank cleaning data sheets, you'll typically see one or two figures reported with regards to reach or cleaning length. On spray balls or other static cleaners you'll typically see a rinse diameter or radius reported - sometimes called the washing radius. On spinners,  you'll typically see two figures reported, and this will be a rinse radius like with the spray ball and then also a scrub radius, which will be lower than the rinse radius. And then on rotary jet cleaners what we see is an effective cleaning jet length or scrub radius reported, and not typically the wetting radius.

 

So why on some tank cleaners do we report both figures? And why on others do we report only one of those figures and what do they mean in terms of when it comes to sizing up tank cleaners. In order to understand that we just need to have a quick step back and look at how tank cleaners actually perform their cleaning?

 

Now there's two primary functions two primary ways in which tank cleaners actually deliver cleaning. The first is mechanical action.
This is the actual impact of the fluid on the side of the tanks to dislodge any residue that may be there.

 

The second important effect is effectively chemical action. This relies on a kind of cascading of the liquid down the walls of the tank to dissolve residues over time. 

So two primary mechanisms: mechanical action and chemical action. Now for completeness any cleaning action also has a heat
element and a time element, but we won't get into those there. Different tank cleaners have a different primacy on one of those two actions - some deliver cleaning primarily through mechanical action and some through this cascade effect. For spray balls, almost all of the tank cleaning is performed by this cascading solvent effect of the wash liquid running down the walls. So spray balls have very little impact, very little mechanical action when it comes to cleaning.

 

The rinse radius  of the spray ball represents the horizontal distance at which the spray ball will deliver water well to the wall of a cylindrical tank. If a scrub radius is reported, it will be some distance below that, but it's not common to have scrub radiuses on spray balls. So when judging  a spray ball's effectiveness we need to ensure that the horizontal distance from the tank wall to the spray ball is at least within the rinse radius. Otherwise, liquid is not going to reach the wall in a sufficient way to perform that cascading down effect, which is the primary cleaning action of a spray ball. Now, as long as we get a decent amount of liquid on the wall, it's going to work OK. What we don't need to do is to have every part of the tank within that rinse radius, so particularly the lower parts of the tank. They're not going to be within that rinse radius, but that's okay, because as long as we're getting it onto the walls further up in the tank and it's flowing down, it's going to perform cleaning well over time.

 

When we move on to spinners, we normally see both the scrub and the rinse radius reported. Now, if we want a light rinse 
 and say it's a fairly easy residue to get off, then we just need to get a good proportion of the water onto the walls in the same way as a spray ball. So we can use the rinse radius for this in exactly the same way as we would get with a spray ball.

 

However, if we want to utilise the spinners, improve mechanical action and drive efficiencies in tank cleaning through that,
because increased mechanical action also means increased efficiency, then we want to keep the distance from the spinner to the tank 
wall within the scrub radius that's reported. Again, this is a kind of judgment call as to whether a decent amount of mechanical action is delivered.


And so the tank cleaning efficiency will be improved. If you want to get the most out of our spinners, we want to keep them within the
scrub radius and not the wetting radius.

 

Now, if we are looking at rotary jet cleaners, we only tend to report the effective jet lengths or scrub radius of that cleaner. The reason for that is that for these cleaners their primary mode of action, their primary mode of cleaning, is actually mechanical action. The cascade effect is still important, but it's a secondary effect. So this being the case, what we want to actually do is keep all of the tank
parts being cleaned within that jet length.

 

So we're not going to just measure from the tank cleaner to the horizontal distance to the wall. What typically we want to do is measure from the tank cleaner to the furthest point of the tank that needs to be cleaned. Normally, that's the kind of bottom corner of the tank. We want to keep that distance within the effective jet length or scrub radius of the tank cleaner. And that way we're going to get good impact on every single part of the tank.  Yes, we'll get the cascade effect as well. But what we want to get is good impact on
all parts of the tank to have really effective cleaning and get the most out of these tank cleaners.

 

Now, with very large tanks or very tall tanks it may not be possible to get to the bottom corner within that jet length, and that's OK as long as the residue isn't too tough, you're going to probably get away with that because we are still getting all of that cascade effect down the wall as well. But if you want to get the most out of them, try and keep every part of the tank within that jet length, if possible.

 

Now, for high pressure cleaners - tank cleaners running at sort of 50 to 100 bar even or even more - those effective jet lengths actually come down quite a lot. For mid-range rotary jet cleaners, the effective jet length goes up with pressure. Sorunning it at 3 bar, it will maybe have a jet length of five metres and running it at ten bar, it may be twelve metres or so. But when it comes to very high pressure cleaners, rotary cleaners, the actual jet length actually comes down. This is somewhat counterintuitive. And the reason for that is is because they're running at such high pressures and because typically they're running at very, very low flow rates, which is the whole point of these tank cleaners, we've got very thin, fast moving needle like jets, and after a few metres, they start to break up and atomise because they just keep moving so fast.

 

So it needs to be noted that those high pressure rotary jet cleaners that run at sort of 50, 100, 150 bar are not suitable for those very,
very big tanks with long clean distances because their effective jet lengths actually come down despite the high pressure.

 

We hope you find that useful. If you have got any other questions on any aspects of tank cleaning, please give us a call.

 

8. What filtration do I need for my tank cleaning/CIP system?

 

Watch our video What filtration do I need? or read on below to find out more.

What filtration do I need? This is a common question we get asked by customers at the Spray Nozzle People when considering an upgrade or a change to a different type of tank cleaning head. So we will endeavour to answer that question as best we can here in this short video.

 

The answer depends very much on the tank cleaning head being used. Now, obviously, the first question to ask is why would you need filtration at all? Aren't we using clean, filtered water for cleaning tanks and in the final rinse?

 

Yes, obviously that's true. You're hopefully not going to need an awful lot of filtration on your final stage of the clean. But for most of the other stages of the tank clean, we'll be using recirculated water to save on water.

 

And in those situations, it's often the case that the particulates from the previous tank, clean pipes and stalks and whatever else is in that tank may find its way into the wash system. So we need to make sure it's filtered before it gets to the tank cleaning head otherwise clogging and problems can occur.

 

So what level do we need? Or to put it another way? What kind of particulate content can the different types of tank cleaners actually handle / pass through them?

 

When looking at spray balls, standard spherical spray balls, these typically will have holes in them about between about one and 2.5 mm in diameter. So obviously, any particulate entering the system that's bigger than one mm is going to get trapped within the spray balls and build up over time and cause clogging. To be on the safe side we'd normally recommend having upstream filtration significantly smaller than the orifice sizes, that is the hole sizes on spray balls. So normally we recommend something like about a 50 mesh filtration, which is about 0.3 mm hole size in the filter. So even with small one mm holes in smaller spray balls, that's going to eliminate clogging. So you're not going to have any problems.

 

Now with bigger spray balls with, say, two or two and a half mm holes in them you could probably get away with 25 mesh, which is 0.7 mm for filtration. So something like that is going to be fine for that type of bigger spray ball. There's also a couple of clog resistant alternatives to spray balls, so there's sticking with static nonmoving tank cleaning heads.

 

 
There's a couple of alternatives to the traditional spray ball that require even less filtration, and this can be a big advantage of these styles of tank cleaner. So very wide angle spiral nozzles can have a spray pattern of up to 270 degrees. You can get a 270 degree tank cleaning nozzle in place and spiral nozzles are naturally clog resistant.

 

They were originally designed to spray slurries and the like. So these will typically have a free passage of around three to five mms. So, you know, technically particles between three and five mms could pass through these nozzles fine. Now we'd still recommend having something a bit smaller than that in terms of your filtration just to be on the safe side. Butsomething like a ten mesh or two mm filtration would be sufficient to filter out any big kind of stalks and large pips and things. And the smaller ones can pass happily through the filter and the spiral nozzle. Now, another design that's recently come on the market is the HydroClaw from BETE Fog Nozzle and this is a unique, patented tank washing nozzle that is specifically designed to be clog resistant.

 

Its design has a huge free passage of around seven mms, meaning it can pass objects about three to four times bigger than that, a standard spray ball. So in most cases, you just need to filter out the very large objects that may find their way into the wash system.
So, you know, a ten mesh or two mm filtration is probably more than adequate for a nozzle of this size, and you can probably get away with no filtration at all in most cases. So moving on to spinning spray balls. Now on the face of it, the slots on the spinners are reasonably large, especially in comparison to the holes in spray balls. So it might look like these types of tank cleaner are actually a lot more clog resistant than spray balls. But the reality is they're not. The reason for this is they run on a kind of ball bearing system as they spin.

 

And that's all exposed to the wash fluid. So any particulate can get into that ball bearing system and gum it up and stop it spinning. So we'd recommend 50 mesh filtration or better for these spinners just to be on the safe side because they can gum up quite easily, so you really want pretty good filtration on these; small bits of grit can build up in the workings and stop them from spinning over time. So we'd recommend something like 50 mesh filtration for these so 0.3 mm and any objects above 0.3 mm being kind of filtered out.
Now, for rotary jet cleaners, it's a similar story, actually. Whilst the jet orifices themselves are actually quite big - they range between 23 mm and anything up to, you know, twelve or 14 mm for the really big ones in diameter.

 

So, on the face of it again, it looks like that's quite a big opening. It should be able to pass through bits of grit and sand quite easily. But again, in reality, the wash fluid itself comes into contact with the internal gears within these tank cleaners, and it's necessary to clean the gears and keep the internals of the tank cleaner self-lubricating and self-cleaning. So again, we need to be quite careful with filtration on these systems, despite the larger nozzle size. So again, we probably recommend something like 50 mesh filtration or better.

 

So again, removing particles much above the 0.3 mm size. And this is just to stop the gears from gumming up over time. And we see this time and time again in, you know, when tank cleaners stop working for whatever reason, it's often the case that stuff has worked its way into the into the mechanisms because they're open to the wash fluid. It's worked its way into the mechanisms and gummed it up over time and it stops spinning.

 

However, there's again a clog resistant version of these available on the market, a clog resistant rotary jet cleaner. Now these standard jet cleaners have greased internal gearboxes, which are not exposed to the wash fluid. Now this this means they can't be a truly hygienic tank cleaning system, so you wouldn't necessarily use them in food processing or applications like that. 

 

But for industrial non-hygienic tank cleaning processes, they're absolutely fine. We sell an awful lot of them into the storm tank cleaning market, for example. And because now that the gears, the internals aren't coming into direct contact with the washer, fluid, grit and sand, and even small bits of rock or whatever, the really hard stuff that can get it can actually pass through the internals of the nozzle quite easily. So again, we want to filter out the really big stuff. We don't want sticks and gobs of algae and really large stuff getting in because that will mess it up over time. But ten mesh, two mm filtration is more than adequate for most of these styles of tank cleaners. You don't really need to worry about filtration too much as long as you're getting the really big stuff out.

 

We hope that was useful to anyone who's looking to upgrade their tank cleaning system and considering what filtration they need. 

 

9. Which CIP system is most water efficient?

Watch our video Which CIP system is most water efficient? or read on below to find out more.

 

So which tank cleaner is the most water efficient? Now this is a question we get asked an awful lot at the Spray Nozzle People and for fairly obvious reasons - water saving is a big concern for most businesses and, for any businesses that are involved in tank cleaning, water can be quite a significant cost. You've got to buy the water in, first of all, then you've got to pump it, then heat it and then you've got to dispose of it. And disposal of contaminated water from tank washes can be quite expensive.
Indeed, so much so that in some water intensive industries such as dairy, it can be one of the most significant overheads. Saving water is a good thing. So which type of tank cleaner is most water efficient?

 

Now there's a short answer to this question, and the short answer is high impact tank cleaners. Generally, the higher the impact tank cleaner, the more water efficiency is going to be. However, there are some nuances to this. There's a slightly longer answer to that question.

 

First of all, let's step back a bit and look at what makes up a clean?

 

Any cleaning action or cleaning operation is made up of four key components - this is 1) mechanical action, which is the physical scrubbing action of the cleaners scrubbing off the residue 2) heat so the hotter the cleaning fluid, the better it will break down residues so the hotter the better 3) Time. Now, then obviously, the longer you actually spend cleaning something with any given cleaning system, the more cleaning it's going to get and then 4) chemical action and this is the solvent quality of the chemicals being used in the clean, so the solvent action of breaking down the residue.

 

Now any cleaning operation will be a combination of these four elements. If you reduce one part or more than one part, you have to compensate by increasing the other parts to make sure that the overall clean is still effective.

 

Now you'll note that water isn't one of those components. So when you think about this, where does water come into this? Water is used in pretty much every cleaning action. So where does the water consumption fit into that four part model and there's two components that it actually fits into?

 

Firstly, water is the main solvent used in almost all cleaning actions. Now we sometimes we don't think of water as a solvent, but in actual fact, it's known as the universal solvent. More things dissolve in water than any other chemical, and it is by far the most common solvent used in any cleaning action.


Now you might add solvents to get water to improve the cleaning action, but nevertheless, the chemical action component of most cleaning operations is largely made up of water. So the chemical action component is definitely part of water consumption.


The other part of the four components that makes up water is time, because all cleaning systems, especially tank cleaning systems, all the time that they're on, they're using water. They're water driven, they're using water as the cleaning medium. They're using water to deliver the other solvents to the tank wall so all the time they're on, they're using water. So water consumption is essentially a function of the chemical action component of the clean and the time component of the clean.



So if we want to reduce water consumption, we therefore need to reduce chemical action and time. So naturally, if we want to keep the clean effective, we need to increase either heat and or mechanical action. Now, we leave heat aside for one moment because that's kind of its own separate entity, and we assume we're keeping heat stable. So if we're keeping it at the same sort of temperature, then we're left with mechanical action.

 

And so in order to reduce water, we need to increase mechanical action. And this is why the general rule that high impact, high mechanical action tank cleaning devices are more water efficient. But there are some exceptions. So rotary jet cleaners, which are the high mechanical action jet cleaners that we have, they must go through a set cleaning cycle in order to deliver their cleaning action to every part of the tank. This is unlike spray balls and spinners, which are low mechanical action tank cleaners and so inherently less efficient. But if the residue is very, very light, the spinners and spray balls will provide instantaneous coverage to the whole tank. And if that residue only takes, say, a couple of minutes to actually come off, then the rotary jet cleaner in the same tank, even though it may be more water efficient overall, still has to maybe go through a 5,6,7 minute, ten minute cleaning cycle just to get its cleaning through every part of the tank.


Therefore, it's going to be less efficient overall because it has to go through that set cleaning cycle, unlike the spray balls and the spinners so there is an exception there. High pressure cleaners, and by this I mean the high pressure cleaners running at 100 or so bar as opposed to the mid-range rotary jet cleaners running at say 10 bar. High pressure cleaners tend to have a quite a short range of their cleaning jets. So when we're looking at very large tanks, these high pressure jet cleaners may need to be moved around within the tank and they have to go through their set cleaning cycle in each stage of the clean.


Now, apart from the hassle of actually having to move around inside a large tank so that their relatively short jets can actually reach each part of it, you've then got to double up the cleaning cycle time so you're doubling up or trebling up the time component, which is a key component in water consumption.


So in very large tanks, it can often be the case that the very high pressure jet cleaners, the 100 bar jet cleaners are actually less water efficient than the ten bar rotary jet cleaners running at medium pressures precisely because you have to do multiple cleaning cycles to move them around within the tank to get an overall effective clean so there's an exception to the rule there as well. Now, obviously, any water savings that you do achieve through increasing the mechanical action through having superior tank cleaners needs to be offset against the additional energy needs and hardware associated with running those higher pressure, high mechanical action systems.


And this is particularly true when it comes to the high pressure systems, the 100 bar type system, because they're going to need expensive pumps and expensive pipe work. And all the rest of it. Less so, but there's still some truth in it, for the mid-range pressure rotary jet cleaners, you still need to take into account those additional hardware and piping costs when compared to spinners. So even though the overall water savings are going to be there in terms of clean water use per cycle, that may be offset by the additional hardware costs as well.


So again, each tank cleaning situation is unique and needs to be analysed, but this answer hopefully gives you some general rules with which to start making decisions. Now, if you need any advice on any of this and come and talk to us, we're the experts.

Tank Washing Engineering Considerations

Tank Washing Nozzle Designs

Tank Wash Nozzle Selection Table