SELECTION This product is to be utilised with clean fresh water, even slightly activated with normal detergents. For use involving different or corrosive liquids, contact the PA Technical department. Appropriate filtration should be installed when using impure liquids. Choose the valve in line with the working data of the machine where to be installed (permissible pressure, maximum flow rate and rated temperature of the system). In any case, the pressure of the machine must not exceed the permissible pressure marked on the valve. OPERATION The valve regulates the pressure of the system by altering the flow discharged by the bypass. The adjustment is carried out by changing, by means of a piston, the position of a ball that partially shuts the bypass opening. At gun closure, a check valve closes and isolates the part of the circuit downstream of the valve: the pressure increase that remains trapped is used to activate the complete opening of the bypass. All the flow supplied by the pump is therefore discharged at low pressure through the bypass and the pump works at low pressure. INSTALLATION This product is intended to be incorporated on a finished machine.On a system that produces hot water, this accessory must be fitted upstream of the heat generator. On a system that produces hot water, it is advisable to fit in accessories that limit the accidental increase of fluid temperature. Always install a safety valve. It is recommended to use a nozzle with a size that, at gun opened, allows to discharge from the valve bypass at least 5% of the flow supplied by the pump in order to obtain a constant pressure value, an easy adjustment and to avoid troublesome pressure spikes at gun closure. If the nozzle wears out, the working pressure decreases. To reset the pressure back to work level, it is necessary to replace the worn out nozzle. When a new nozzle is fitted, re-setting of the system to its original working pressure is necessary. DISCHARGE SYSTEM AND WATER ADDUCTION It is recommended to return the bypass discharge into a tank. It is also advisable for the tank to be fitted with deflectors to reduce possible turbulence and air bubbles generated by the omission of the bypass flow which could be harmful for the pump. When large flow volumes, close tho the max flow rate, are used, it is not advisable to return the bypass flow to the pump as this may cause dangerous pressure spikes, harmful for the pump. PRESSURE ADJUSTMENT/CALIBRATION The desired working pressure must be adjusted with the system running and the gun opened. Adjust the pressure by screwing or unscrewing the adjustment screw/knob. The operation is easier if the correct nozzle has been chosen (see paragraph “installation”). When screwing the adjusting screw, a consequent pressure increase must be matched. If, before reaching the desired pressure, there is no pressure increase, do not insist but check the correct ratio nozzle/flow rate – pressure.