Pumps

Pumps play a crucial role in most spray delivery systems. There are many different types of pumps available and it can be a quite bewildering choice. Our approach to pump selection is practical and straightforward. We will always work back from the spray nozzle to try to determine which pump is best suited to delivering the spray the application requires. To be clear, our business is sprays and spray systems; as such, pump selection is always made with the spray delivered by the overall system in mind. 

Factors to consider

Maximum flow rate

Maximum pressure (head)

The normal required operating pressure at the spray nozzle should be used as a primary piece of information when specifying the delivery pump. Any suitable pump will obviously need to be able to maintain at least that pressure. When selecting pumps, we will look are pump curves to find a pump that will deliver the required pressure comfortably on its fluid delivery curve. We don’t want a pump that will struggle to keep up or one that is over specified, as this will be inefficient.

One vital factor to consider is what lies in between the pump and the nozzle?  Pressure loss calculations need to be performed and this will then determine the pressure required to be delivered at the pump, and this may well be significantly higher than the pressure that needs to be “seen” by the nozzles. For example, if the fluid needs to rise 5 meters from where the pump is situated to where the nozzles are then half a bar of fluid pressure will be lost due to gravity. So, if the nozzles need to see 5 bar to deliver the required flow rate, the pump will need to generate at least 5.5 bar of pressure to meet this.

Fluid properties

If spraying anything other than water, we need to understand what the fluid properties are. Many pumps can handle fluids with higher or lower specific gravities or viscosities, but these properties will affect how much flow and pressure will be delivered, and so must be understood. In addition, specialist pumps may need to be selected to handle fluids that are chemically aggressive.

Fluid contamination

Many pumps can handle a certain degree of particulate with the fluid being pumped, but some are less tolerant. In order to select the correct pump for the spray system, we need to understand the particulate content of the fluid at the pump. This might be quite different from the particulate content of the liquid at the nozzle as a filtration system may sit between the nozzle and the pump.

Hygiene

For food, pharmaceutical and other hygienic applications a hygienic design pump will be required. This will often be down to material selection. Most pump manufacturers will have their products segmented as being suitable or unsuitable for hygienic applications. Obviously, when we are designing spray systems for food and pharma we will default to hygienic pumps in the specifications.