Product Manual 128 PQC Series Control Valve 1" 1500 lbs

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Changing Main Spring RangeUnless otherwise indicated, refer to Table 3 forparts listings for replacement packing and trimassembly, Figure 3 for packing and trimassembly key numbers and Figure 5 for controlvalve assembly key numbers.1. Isolate off the control valve from allpressure, and release pressure from valvebody and actuator.2. Release pressure and drain the processmedia from both sides of the valve body.Ensure the valve is completely closed.3. If necessary, disconnect the input signaltubing; remove the diaphragm casing nuts(Key 15), cap screws (Key 14) and upperdiaphragm casing (Key 1).4. For fail-close action applications, installmain springs (Key 12), using quantities anddescriptions as outlined in Table 2.Note: It is important to avoid loosening thestem-nut (Key 15), as this may prevent thevalve from shutting off or from fully openingat full pressure, and resulting in the need forcomplete disassembly of the control valve toproperly install the stem and diaphragm.5. For fail-open applications, unfasten thelocknut (Key 16), remove the flat washer(Key 33), diaphragm (Key 35), diaphragmplate (Key 34), spring plate (Key 2), andmain springs (Key 12).6. Refer to Table 2 and install main springs asindicated.7. Reassemble the removed parts (Keys 2, 34,35, 33, and 16). The locknut (Key 16) mustbe tightened to 12 foot-pounds (16 N•m).8. Attach the upper diaphragm casing usingthe cap screws, and casing nuts, tighteningin an even crisscross pattern to avoidcrushing the diaphragm. Tighten to 15 footpounds(20 N•m).9. Reconnect the input signal tubing to theactuator connection of the appropriatediaphragm casing.Reversing Action or Replacing ActuatorPartsUnless otherwise indicated, refer to Table 3 forparts listings for replacement packing and trimassembly, Figure 3 for packing and trimassembly key numbers and Figure 5 for controlvalve assembly key numbers.1. Isolate the control valve from all pressure,and release pressure from valve body andactuator and ensure the valve is completelyclosed.2. Remove the input signal tubing, diaphragmcasing nuts (Key 15), cap screws (Key 14)and upper diaphragm casing (Key 1).3. Remove the following:3.1. Main springs (Key 12)3.2. Stem nut (Key 15)3.3. Locknut (Key 16) and lock washer (Key4)3.4. Spring plate (Key 2)3.5. Diaphragm plate (Key 34) anddiaphragm (Key 35)3.6. Flat washer (Key 33)4. Unscrew the four nuts (Key 32) from thescrews of the lower diaphragm casing. Afterdisconnecting the input signal tubing,remove the actuator from the valve bodyalong with attached trim parts.5. Remove the following:5.1. Valve plug (Key 25)5.2. Packing box washer (Key 27)5.3. Slide the packing box (Key 28), O-ringretainer (Key 18), stem O-ring (Key 19)and the diaphragm casing O-ring (Key31) off the stem.6. Replace the valve stem, bottom stem nut orlock nut (Key 15 or 16) as required.7. Refer to Figure 4 and ensure that the lowershoulder of the bottom stem nut (Key 15)(for fail-open assembly) or locknut (Key 16)(for fail-close assembly) is the properdistance from the plug end of the stem.6
Reversing Action or Replacing ActuatorParts cont’d8. Perform the following assembly sequencesas necessary to achieve the required controlvalve action:8.1. Fail–close action: install the followingparts: flat washer (Key 33), diaphragm(Key 35), diaphragm plate (Key 34),spring plate (Key 2), lock washer (Key4) and stem nut (Key 15). Tighten stemnut to 12 foot-pounds (16 N•m).8.2. Fail-open action, install the followingparts: lock washer (Key 4), springplate, diaphragm plate, diaphragm, flatwasher (Key 33) and locknut (Key 16).Tighten the locknut to 12-foot-pounds(16 N•m).9. With fail-open application, place the mainsprings (Key 12) into the lower diaphragmcasing, ensuring that the lower ends of thesprings rest over the weld stud heads of thelower diaphragm casing.10. Following steps 6 through 10 of the“Replacing Packing and Trim” section, installpacking and trim parts to secure the stem.11. When reversing action from previousdirection, move the vent (Key 3) to the 1/4-inch NPT actuator connection of the lowerdiaphragm casing (for fail-open action) orupper diaphragm casing (for fail-closeaction).12. For fail-close application, place the mainsprings so that they rest in the spring plateholes and will not touch the upperdiaphragm casing vent boss.13. Mount the upper diaphragm casing, capscrews, and casing nuts, tightening in aneven crisscross pattern to avoid crushingthe diaphragm. Tighten to 15 foot-pounds(20 N•m).14. Replace the actuator and attached trim partsinto the valve body (Key 26) with nuts (Key15) to the lower diaphragm casing integralassembly screws. Tighten nuts to 15 footpounds(20 N•m).15. Reconnect the input signal tubing to theactuator connection of the appropriatediaphragm casing.Parts OrderingCVS 128-PQC valves have individual serialnumbers, found on the valve nameplate. Pleaserefer to that number when ordering parts orcontacting your CVS Controls SalesRepresentative. Individual parts numbers arelisted as follows. Please include these numberswhen ordering replacement parts.7
Page 1 and 2: Instruction ManualCVS 128PQCSeries
Page 3 and 4: InstallationWarning:Service conditi
Page 5: Replacing Packing and Trim continue
Page 10 and 11: Parts ListKey Description Part Numb
Page 12: Head Office3900 - 101 StreetEdmonto

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