Control valve installation manual

Valve and pressure tank should be as close together as possible. There should be no more than ' of piping between the valve and the pressure tank. Pressure tank pre-charge should be psi lower than the pressure switch start point. A water line at least 8" or longer and no larger than tank inlet size should be used to connect the tank. Pressure switch must be installed on the line going into the tank, as close to base of the tank as possible.

Pressure switch should never be installed directly on the main line. Make sure adjusting stem is loosened completely by turning counter clockwise until you feel it is no longer making contact with the spring.

Set the pressure switch to desired settings. Open a small water outlet to turn pump on. When pressure steadies at the desired system pressure, tighten the lock nut on adjusting stem of the pilot valve. Valve setting is complete. Note: If water hammer occurs on pump start up, you must set valve pressure and cut in pressure the same.

Before installation, the system should be checked so that we could know if the pressure is on the wrong side of the disk if so it could damage the valve. Maintenance must be done periodically for valves so that the service life will be better. If a leak is seen then it must be taken care, sometimes it can be done by tightening a packing gland nut.

Loose hangers could allow sections of a line to sag. Valves that are used for a long time and subjected to constant service must need gland tightening, replacing or a complete overhaul.

The valve can be checked visually to know if the seat and disk make good contact with each other and this known as spotting valves. Grinding valves grinding can be done manually to remove irregularities by grinding together the contact surfaces of the seat and disk.

It is an air relay that is used between the controller output and the valve diaphragm. It will assure the exact position of the valve stem in accordance with controller output. Spring and diaphragm are the most popular actuator type, the net output thrust is different between diaphragm force and opposing spring force.

Output thrust is required and supply air pressure available dictate size. Diaphragm actuators are simple and dependable. This type is operated pneumatically with the help of high pressure, it provides high thrust and fast stroking speed. This actuator can give maximum force in both directions. Manual actuation — Manual actuation is done by the operator and it is done according to the system requirements.

Pushbuttons, pedals are needed for manual actuation. Connect air tubing between the controller and diaphragm actuator or the valve positioner if one is in use. Use tapered expander. Check if control valve responds properly through rated travel in relation to the changes in operating pressure in the diaphragm. Rated travel is shown by the position of the indicator on the valve stem relative to the indicator plate scale on the yoke.

Manually operate control valve fitted with manual operating devices through the rated travel range to check freedom of movement. Return manual operating devices to its stand-by position. Place control valve in operation in accordance with the operating instructions provided with controller or other operating device.

To reduce maintenance time refer to proper drawing and follow the steps shown below for applicable maintenance. Renew the valve stem packing if control valve has been in service beyond normal maintenance interval with packing showing signs of wear.

Wear will be indicated by leakage which can not be corrected by minor tightening of packing flange. Caution: Over-tightening of the packing flange can cause erratic operation of the valve. Note: Where graphite packing is used, additional packing can be installed to overcome minor leakage without dismantling the control valve.

Close the inlet and outlet stop valves and check that valve body is not under pressure. Remove nuts and lift packing flange and packing follower in sufficient height on the valve stem to apply the split packing around diameter of valve stem. Lower packing follower over the new packing, lower packing flange and tighten sufficiently with nuts to stop leakage See Below Figure.

During start-up some leakage may be observed. If pressure is raised considerably, the packing may leak slightly. For best results, it is recommended that after packing installation and adjustment the valve to be fully stroked approximately 20 times to break-in the packing and reduce stem friction.

Close inlet and outlet stop valve and relieve all pressure from piping involved. Loosen hex. Remove the lock nut holding the actuator to the bonnet and lift off the actuator. Remove actuator from valve body assembly as previously described in disassembly of diaphragm actuator from valve body assembly.