Trouble-Shooting Pneumatic Valves
- VALVE WILL NOT SHUT OFF.
- VALVE WILL NOT OPEN OR DELIVER WATER.
- VALVE WILL ONLY RUN A SHORT TIME AND DOES NOT RESPOND TO TIMER ADJUSTMENT.
1. Remove 1/8” air tube from fitting beside timer. If the valve shuts off after a short time, turn the timer adjustment counter-clockwise several turns. Re-connect the tubing making sure the connection is sealed properly (tubing will not slip or come off if tugged gently). Re-adjust timer for desired cycle time.
2. Turn off water to the valve. Remove the valve top by removing the (4) screws securing it. Note the position of the tube connector and timer so the valve top can be properly re-assembled in the same position. Remove the valve operator exposing the water chamber of the valve. Check the rubber diaphragm assembly for possible debris. Check the diaphragm to be sure the rubber is properly seated into the plastic post. The plastic post has a groove that the rubber diaphragm fits into and there should not be any bulges in the rubber when it is properly seated. Check the hole through the plastic post to be sure it’s free of debris. Turn the diaphragm assembly over and find the small circle near the edge of the rubber. There is a small hole in the middle of the circle that should be free of debris. Rinse the assembly with clean water to remove any debris. Also, rinse the orifice plate and the separator cup in the valve top, making sure the small spring in the separator cup (above the orifice plate) is not dropped or lost. If any part of the diaphragm is damaged, replace the entire diaphragm assembly using part # 16426 (pvk-2 diaphragm kit). Clean any debris from the valve base and the valve seat before re-assembling. Re-assemble the valve and adjust the timing to the desired cycle length.
2. Remove the 1/8” plastic tubing from the back of the pushbutton diaphragm and suck on the end. If water flows, the valve is operating properly but there is an air leak in the tubing connections, the tubing, or the pushbutton diaphragm. Also, it is possible that the timer has been opened (turned counter-clockwise) so far the vacuum can not be held. Close the timer (turn clockwise) to see if the valve will operate. If yes, adjust the timing for the desired cycle.
3. Check the flow control orifice located in the valve outlet fitting to be sure it is not blocked by debris. If blocked, clear debris by blowing air through it from the tubing end of the fitting. Do not force any tools through the orifice as this may damage or distort it and cause improper operation.
4. Check the pushbutton actuator diaphragm for leakage by removing the diaphragm from the back of the pushbutton and from the air tubing. While holding your finger over the end of the tubing connection to seal it, push the rubber diaphragm toward the back using your finger in place of the pushbutton. If the tubing fitting is sealed properly with your finger, the rubber diaphragm should be held back away from the front of the diaphragm housing. If it returns to the front of the
housing, it is not holding a vacuum and must be replaced. This test should be repeated several times before deciding the diaphragm must be replaced as it is difficult to hold your finger over the hole in the tube fitting to properly seal it.
This is one of the most common complaints. In most cases, this is a result of an air leak in the air tubing connections either at the pushbutton end or the valve end of the tubing. If the tubing is connected using a white plastic nut, gently give the tubing a quick tug. If it comes out of the fitting, re-insert it, making certain it “bottoms out” in the fitting. Using gentle force, tighten the plastic nut one-quarter turn. Repeat as necessary until the tubing is held tightly in place.
If the tubing is connected using a small brass nut (especially on showers) on the pushbutton end, it is common to find the nut has been over-tightened. This causes the seal between the tube fitting and the diaphragm or valve body to leak air. Often, loosening the nut is only possible by removing the fitting. When re-installing the fitting, it is important to just tighten the fitting firmly. Excessive force should not be applied. The brass nut should be slipped over the tubing end and then the tubing is pushed onto the barbed end fitting. The tubing nut should then be tightened only by using the fingers. The seal on this type of connection is effected on the inside of the tubing and the barb on the fitting. The brass nut serves only to prevent the tubing from inadvertently being pulled off the barb. The brass nut is not designed to seal the connection.
It should be noted that the ends of the 1/8” tubing should be closely checked for splitting or cuts. Also, inspect the tubing to be sure there are no kinks or bends to prohibit airflow within the tubing. If the tubing is damaged or kinked, it must be replaced. The ends of the tubing should be cut square for the best results.