The following chart outlines some common problems with manual and actuated ball valves. Consideration should also be given to the length of service and application conditions as the product may have reached the end of functional life and may simply need to be replaced.
Gemini Valve welcomes direct contact to assist with troubleshooting. You can reach us at 800 370-0936, 603 895-4761, or e-mail service@geminivalve.com
Valves: |
Problem |
Possible Cause(s) |
Action |
Leakage at stem |
Stem seal worn out |
76, 86, 96, 309 series - replace valve 89 & 98 series - repair using valve repair kit (VRK) |
Insufficient stem nut torque |
Re-adjust by tightening the stem nut until the belleville springs become fully compressed |
Stem nut over tightened |
Permanent damage to stem seal76, 86, 96, 309 series - replace valve89 & 98 series - repair using valve repair kit (VRK) |
Incorrect stem trim (hardware) |
Consult the appropriate instruction sheet for the required hardware and proper assembly |
Stem side loading due to improper actuator mounting |
Remove and remount valve to allow valve to sit naturally in valve retainer. Tighten valve retainer (76, 86 & 96 series) assembly screws in a uniform fashion |
Leakage at seats |
Application outside pressure / temperature rating of valve |
Immediately replace with valve properly rated |
Worn seats |
76, 86, 96, 309 series - replace valve89 & 98 series - repair using valve repair kit(VRK) |
Pressure spikes |
Prevent by use of snubbers |
Stem twisted causing mis-alignment of ball port |
76, 86, 96, 309 series - replace valve89 & 98 series - replace stem |
Leakage at body to endplug joint (series 86, 96 & 309 series) |
Enplug disturbed while installing valve |
Check, retorque to specifications |
Leakage at body joint (series 89) |
Incorrectly tightened assembly bolts |
Check, retightened to specifications |
Media incompatible with standard viton body seals |
Consult gemini for optional body seal material |
Leakage at pipe joint |
Mating pipe cross threaded |
Replace valve and fitting |
Lack of proper piping practices |
N/A |
Poor thread quality of mating fitting / pipe |
Replace fitting / rethread pipe with new dies |
Pneumatic Actuators: |
Problem |
Possible Cause(s) |
Action |
Actuator will not cycle |
No air or inadequate supply |
Check air supply at the actuator using a gauge |
Obstructed air supply or exhaust lines |
Check all air supply and exhaust lines to and from actuator to ensure they are not bent, cut or obstructed |
Pilot / solenoid valve not functioning |
Remove pilot / solenoid valve from actuator to check |
Ball valve seized or elevated torque due to media conditions |
Remove actuator from valve and try to cycle actuator, if actuator cycles try to cycle valve using flats of stem, if torque appears to be high or valve cannot be cycled examine valve for possible causes |
Restricted air delivery |
Ensure proper air delivery to actuator which includes i.d. of pilot / solenoid orifice and i.d. of air supply and exhaust lines for length to i.d. requirements |
Actuator cycles sluggishly |
Improperly adjusted stem nut |
Check and adjust to specifications |
Torque (changing), requirements of valve starting to exceed actuator torque output |
Examine media to determine if possible build up is occurring on ball or seats, direct consultation of gemini valve recommended |
Restricted air flow due to use of exhaust muffler |
Remove muffler |
Pilot / solenoid valve speed controllers being used |
Adjust to allow full operation |
Limit Switches: |
Problem |
Possible Cause(s) |
Action |
Will not send signal |
Incorrect positioning of actuator limit switch cam |
Review limit switch mounting & wiring instructions |
Incorrect adjustment of micro switches |
Adjust switch point |
Set screw on cam loose |
Remove bracket & retighten |
Improperly wired |
Review wiring schematic inside limit switch cover |
Limit switch probe damaged |
Replace limit switch |
Actuator not cycling |
See above pneumatic actuators, actuator will not cycle |
