Nozzles for scoring 

The use of water jets to score a bread or cake-based product is a common application.  A solid stream nozzle is required to deliver the necessary impact.

Spray control

The control of such systems is paramount especially on conveyors presenting multiple products at one time.  A bank of nozzles, one for each product, will need to be carefully configured to spray only when required.  Any imprecision in the on/off cycle could result in product defects. 

Three levels of control 

There are three main methods for controlling the on/off cycle of spray nozzles.

1. A basic fluid line valve is the first level of control and is rather unresponsive as the nozzle takes time to react to pressure drops.

2. The next level up is an air actuated nozzle.  This has a spring-loaded pneumatic cylinder controlling the on/off cycle of the nozzle.  In these setups the fluid pressure is maintained at a constant level and so the nozzle does not have a lag in spraying whilst pressure builds up.

3. The final level of control can be achieved by having a solenoid valve built directly into the nozzle.  These electrically actuated nozzles offer the fastest response time. 

Nozzle selection

Standard hydraulic nozzles will only be suitable if the scoring jet is designed to flow continually.  For other setups that required precission on/off cycles either air or electrical nozzle actuation will be required.  Air actuated nozzles can achieve about 3 on/off cycles per second and so are responsive enough for many water scoring applications.  For faster, more precise control, electrically actuated nozzles can be cycled 150 times per second.  They also have the advantage of being directly controlled by an electrical signal whereas the air actuated nozzles are controlled via a solenoid valve on the air supply which means there will be a small lag in responsiveness.