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When troubleshooting the operation of a sealed motor valve, it is always advisable to install gauge valves and pressure gauges upstream and downstream of the valve. Gauge ports are provided on the inlet and outlet flange of each sealed motor valve for this purpose. Determining the inlet and outlet pressure during operation of the valve will add significant value to the solution to the problem. If the motor is removed or the valve serviced, always
recalibrate the valve before returning valve to automatic
operation. | |||
| Problem | Symptom | Cause | Check/Do |
| 1.Valve does not operate | Motor does not pulse when milliamp signal is changing. | 24 VAC lacking | Check 24VAC across valve wires #1 & #2 |
| Mis-wired | Double check numbers printed on power head wires vs. wiring diagram. | ||
| 4-20ma wires reversed | Follow wiring diagram to be sure wire goes from positve on one terminal to negative terminal around the 4-20ma loop | ||
| No 4-20ma signal to valve | Check milliamp signal to power head on either wires 3 or 4. install milliamp meter in series with 4-20ma signal to power head to confirm proper signal | ||
| Valve position does not change with change to 4-20ma signal. Motor pulses | Excess dirt in valve | Clean valve and recalibrate | |
| Can dented causing interference with rotor | Replace Can and recalibrate valve. Use MOVT tool to protect Can when servicing valve. | ||
| 2. Valve will not close | Valve position does not change with change to 4-20ma signal. Motor pulses | Insufficient voltage | 24 VAC wires undersize. Check wire size and replace if necessary |
| Shaft thread worn excessively | Remove power head. Use manual tool MOVT to rotate rotor. Rotor should rotate smoothly. If not, disassemble valve, clean valve & threads, replace V-port if threads worn excessively | ||
| Excess dirt or free water in valve | Clean valve and recalibrate | ||
| 3. Valve will not open | Valve position does not change with change to 4-20ma signal. Motor pulses | Insufficient voltage | 24 VAC wires undersize. Check wire size and replace if necessary |
| Shaft thread worn excessively | Remove power head. Use manual tool MOVT to rotate rotor. Rotor should rotate smoothly. If not, disassemble valve, clean valve & threads, replace V-port if threads worn excessively | ||
| Excess dirt or free water in valve | Clean valve and recalibrate | ||
| 4. Valve will not open-3" and 4" sizes only | Valve position does not change with change to 4-20ma signal. Motor pulses | Outlet pressure more than 10 psi higher than inlet pressure to valve | Increase inlet pressure or decrease outlet pressure |
| 5.Valve does not maintain Temperature | Temperature too high | Valve undersize | run valve wide open manually to confirm valve is undersize |
| Valve not calibrated | Calibrate valve | ||
| 6.Valve does not maintain Level- Model HMMR | Erratic level readout, level too high or too low | Level sensing probe calibration incorrect | recalibrate liquid level probe |
| 4-20ma loop erratic | Install independent properly grounded 24VDC power supply to confirm proper reading | ||
| Level too low (or too high as high side control) | Valve undersize | Run valve wide open manually to confirm valve is undersize | |
| Level too low | Lack of liquid | Verify liquid is present. Check for flash gas in line | |
| Wide swings from set point | Valve oversize | Replace with smaller valve or V-Port | |
| Pilot Vessel Undersized | Review system capacity requirements | ||
| Flash gas at inlet to valve | Review piping sizes, liquid level in receiver | ||
| 7.Valves does not maintain Pressure | Pressure too high or too low | Valve undersize | Run valve wide open manually to confirm valve is undersize |
| 8. Valve Hunts | Does not maintain constant level | PID constants not set properly | For liquid level control, set I and D to zero, and adjust P to minimize valve position swings. Add I if valve is too "lazy". |
| Does not maintain constant temperature | PID constants not set properly | Speed up temerature response by moving temperature sensor location closer or into vessel. If sensor is in a well, speed up sensor response time by using thernal oil in well. Set I and D to zero, and set P to minimize swings under load. Add I if valve is too lazy. Be wary of using auto-tuning function of controller on chiller applications | |
| Does not Maintain constant pressure | PID constants not set properly | For level pressure control, set I and D to zero, and adjust P to minimize valve position swings. Add I if valve is too "lazy". | |
| Wide swings from set point | Valve oversize | Check sizing-consider reduced V-Port | |
| 9. Valve position feedback does not work (customer supplied controller) | Readout is zero | Power supply missing | install 24VDC power supply |
| Readout incorrect | Disturbance from other devices on 4-20ma supply | Install independent 24VDC power supply to confirm proper reading | |
| Readout is above 100% and does not change | Power head was removed and reinstalled | Recalibrate valve. See instructions | |
| 10. Hansen PCML Liquid Level Controller does not control properly | Readout is[ LL] | Milliamp reading below 4.0 | Valve is closed. Controller reads LL when milliamp signal is below 4.0 ma. Control is OK |
| Valve hunts | PID constants not set properly | Reset controller to factory default PID tuning parameters. If valve hunts under load, double P. If valve is "lazy" under load, halve P. | |
| Readout is [HH] | Milliamp reading above 20 ma | Valve is wide open. Controller reads HH when milliamp singal I above 20 ma. Control is OK | |
| Readout does not change | Improper wiring | Check wire numbers to correspond with wiring diagram. Check polarity | |
| Controller reads OPEN | Improper wiring or controller failure | Check wire numbers to correspond with wiring diagram. Check for 4- 20ma signal. Replace control module. | |
| Controller is damaged due to 2 24VDC power supplies in loop | Remove external power supply and replace control module | ||
| Wide swings from set point | Valve oversize | Check sizing-consider reduced V-Port. Pilot vessel undersized. Flash gas at inlet to valve | |
| Pilot Vessel Undersized | Review system capacity requirements | ||
| Flash gas at inlet to valve | Review piping sizes, liquid level in receiver | ||
| 11. Hansen PCMT controller does not control properly | Temperature not maintained or is slow to respond | Temperature sensor not position properly | For chillers, position sensor within 1 foot or less from the outlet of the chiller. For air sensor, position sensor in air stream. Program valve to safe position when fluid being sensed stops flowing. |
| Readout does not change | Improper wiring | Check wire numbers to correspond with wiring diagram. Check polarity | |
| Valve hunts | PID constants not set properly | Speed up temerature response by moving temperature sensor location closer or into vessel. If sensor is in a well, speed up sensor response time by using thernal oil in well. Set I and D to zero, and set P to minimize swings under load. Add I if valve is too lazy. Be wary of using auto-tuning function of controller on chiller applications | |
| Wide swings from set point | Valve oversize | Check sizing-consider reduced V-Port | |
| 12. Hansen PCMP Controller does not control properly | Readout does not change | Improper wiring | Check wire numbers to correspond with wiring diagram. Check polarity |
| Wide swings in set point | Valve oversize | Check sizing-consider reduced V-Port | |
| >BACK TO TOP< | |||