1. INTRODUCTION (G)72K Series Installation and This manual provides instructions and procedures necessary to install, Operation Instruction operate and troubleshoot the Moog Inc. Series 72K or G72K intrinsic safety protected industrial serovalve. The (G)72K series valves are electrical equip- Electrohydraulic Servovalve ment for hazardous areas with intrinsic safety or non-incendive protection.The identification is II 1G Ex ia IIC/IIB T4 KEMA 02 ATEX 1015 X, or II 3G Ex nA II T3 KEMA 02ATEX1016 X, 0344 per ATEX directive 94/9/EC.They are intended for directional, position, velocity, pressure and force control in hydraulic control systems that operate with mineral oil based fluids. Others on request. 2. OPERATION The Moog Inc. Series (G)72K Electrohydraulic Servovalve consists of a polarized electrical torque motor and two stages of hydraulic power amplification. The motor armature extends into the air gaps of the magnetic flux circuit and is supported in this position by a flexure tube member.The flexure tube acts as a seal between the electromagnetic and hydraulic sections of the valve.The two motor coils surround the armature, one on each side of the flexure tube. The flapper of the first stage hydraulic amplifier is rigidly attached to the midpoint of the armature.The flapper extends through the flexure tube and passes between two nozzles, creating two variable orifices between the nozzle tips and the flapper.The pressure controlled by the flapper and nozzle variable orifice is fed to the end areas of the second stage spool. The second stage is a conventional four-way spool design in which output ELECTROHYDRAULICVALVE CUT-AWAY flow from the valve, at a fixed valve pressure drop, is proportional to spool displacement from the null position.A cantilever feedback spring is fixed to the flapper and engages a slot at the center of the spool. Displacement of the spool Nozzle deflects the feedback spring which creates a force on the armature/flapper Polepiece assembly. Coil Connector Armature Input signal induces a magnetic charge in the armature and causes a Magnet deflection of the armature and flapper.This assembly pivots about the flexure Flexure Tube Filter tube and increases the size of one nozzle orifice and decreases the size of the Inlet Orifice Feedback Wire other. This action creates a differential pressure from one end of the spool to the other and results in spool displacement.The spool displacement causes a force in the feedback wire which opposes the original input signal torque. Spool Filter movement continues until the feedback wire force equals the input signal force. Spool B A Return C CA AU UT TIIO ON N Supply Pressure DISASSEMBLY, MAINTENANCE, OR REPAIR OTHER THAN IN ACCORDANCE WITH THE INSTRUCTIONS HEREIN OR OTHER SPECIFIC WRITTEN DIRECTIONS FROM MOOG WILL INVALIDATE MOOG’S OBLIGATIONS UNDER ITS WARRANTY AND YIELD THE INTRINSICALLY Figure 1 Moog Series 72K and (G)72K SAFE PROTECTION PERMIT NULL AND VOID. Upon system startup and prior to mounting the servovalve, the entire 3. ELECTRICAL INFORMATION AND INTRINSICALLY hydraulic system should be purged of built-in contaminating particles by an SAFE CIRCUIT SAFETY PARAMETERS adequate flushing. The servovalve should be replaced by a flushing manifold and a. A wide choice of coils is available for a variety of rated current the hydraulic circuit powered up under conditions of fluid temperature and fluid requirements. The torque motor coil leads are attached to the connector velocity reasonably simulating normal operating conditions. New system filters so external connections can provide series, parallel or single coil are installed during the flushing process whenever the pressure drop across the operation. The valves are equipped either with an MS type connector or filter element becomes excessive. The flushing processes should turn over the with pigtail leads for electrical wiring. Refer to installation drawings of the fluid in the reservoir between fifty to one hundred times. specific model for details. Servovalve coils should be driven with current to To maintain a clean hydraulic system, the filters must be replaced on a provide consistency throughout the temperature range. periodic basis. It is best to monitor the pressure drop across the filter assembly b. The (G)72K valves are approved for intrinsically safe protection per EN and replace the filter element when the pressure drop becomes excessive. In 60079-11. The approved safety parameters are listed in the following table addition to other filters that are installed in the hydraulic circuit, it is for all the coils used by (G)72K series. Coil number is marked on the valve recommended that a large capacity, low pressure ß ≥75 filter be installed in the 3 nameplate. return line. This filter will increase the interval between filter element replacements and greatly reduce the system contamination level. Coil Configuration Marking U (MAX) I (MAX) i i G4220-031 (single, series, parallel) Ex ia IIB T4 12 V 120 mA 6. INSTALLATION G4220-051/098 (single, series, parallel) Ex ia IIB T4 12 V 240 mA G4221-001 G4220-042 (single) Ex ia IIC T4 16 V 160 mA The Moog (G)72K series industrial servovalve may be mounted in any G4221-001 G4220-042 (single) Ex ia IIC T4 24.4 V 85 mA position, provided the servovalve pressure, piston, and return ports match respective manifold ports. The mounting pattern and port location of the G4220-031 (single, parallel) Ex ia IIC T4 30 V 26 mA 3 servovalve is shown on Figure 4. The servovalve should be mounted with /8-16 G4220-031 (series) Ex ia IIC T4 30 V 18 mA x 2.00 inch long, socket head cap screws. Apply a light film of oil to the screw G4220-051/098 (single, parallel) Ex ia IIC T4 30 V 19 mA threads and torque to 175 inch-pounds. Wire mating connector for desired coil G4220-051/098 (series) Ex ia IIC T4 30 V 12.7 mA configuration and polarity. Thread connector to valve. c. The (G)72K valves are approved for non-incendive operation for supply 7. MECHANICAL NULL ADJUSTMENT current not to exceed 50 mA dc. d. When making electric connections to the valve, appropriate measures must It is often desirable to adjust the flow null of a servovalve independent of be taken to ensure that locally different earth potential do not result in other system parameters. The “mechanical null adjustment” on the Moog (G)72K Series servovalve allows at least ±20% adjustment of flow null. The “mechanical excessive ground currents. When barriers are required for the hazardous null adjustor” is an eccentric bushing retainer pin, located above the port location, hazardous area (field) wiring must meet the requirements of the designation on the valve body (see Figure 2) which, when rotated, provides barrier manufacturer. All barriers must be mounted and installed in control of the bushing position. Mechanical feedback elements position the compliance with the barrier manufacturer’s requirements. Twisted pairs of spool relative to the valve body for a given input signal. Therefore, a movement 18-20 gage wire are recommended. If shielded wire is used, connect shield of the bushing relative to the body changes the flow null. wire to earth ground only at the barrier strip. Adjustment Procedure 4. SPECIAL CONDITIONS FOR SAFE USE 3 Using a /8 inch offset box wrench, loosen the self-locking fitting until the Because the enclosure of the apparatus is made of aluminum, if it is null adjustor pin can be rotated. (This should usually be less than 1/2 turn). mounted in an area where the use of category 1 G apparatus is required, it 3 DO NOT remove self-locking fitting. Insert a /32 inch Allen wrench in null must be installed such that even in the event of rare incidents, ignition sources 3 adjustor pin. Use the /32 Allen wrench to rotate the mechanical null adjustor due to impact and friction sparks are excluded. pin to obtain desired flow null.Torque self-locking fitting to 57 inch lbs. When the electrohydraulic servovalve is used in an application for type of explosion protection intrinsic safety “i”, the appropriate box on the data label Note: must be scored. When the electrohydraulic servovalve is used in an application Clockwise rotation of null adjustor pin produces flow from port P to port B. for type of explosion protection “n”, the appropriate box on the data label must be scored. After use in an application for type of explosion protection “n”, the Tools and Equipment servovalve cannot abe safely used in a intrinsically safe application. a. Blade screwdriver The screwed cable connector may only be disconnected when the circuit 3 7 3 3 b. Allen wrench set ( /32, /64, /8, /16) is de-energized or when the location is known to be non-hazardous. 1 1 c. No. 4-40 NC by 1 /2 inch screw, /4 -28 UNF x 1 inch screw When used at an ambient temperature ≥70°C, heat resistant cable must d. Torque wrenches be used with a continuous operating temperature in accordance with the 3 e. /8 inch offset box wrench application. f. Tweezers 5. HYDRAULIC SYSTEM PREPARATION To prolong servovalve operational life and to reduce hydraulic system maintenance, it is recommended that the hydraulic fluid be kept at a cleanliness level of ISO DIS 4406 Code 16/13 maximum, 14/11 recommended. The most effective filtration scheme incorporates the use of a kidney loop or “off-line” Figure 2 filtration as one of the major filtration components. The filter for the “off-line” Mechanical Null filtration scheme should be a ß ≥75 filter for maximum effectiveness. Adjustment 3 8. GENERAL SERVICING RECOMMENDATIONS a. Disconnect electrical lead to servovalve. b. Relieve hydraulic system of residual pressure. c. Remove servovalve. 9. TROUBLESHOOTING CHART The following troubleshooting chart list potential troubles encountered, probable causes, and remedies. Potential Trouble Probable Cause Remedy Servovalve does not follow input command 1. Open coil assembly or open coil leads. 1. Return to factory. signal. (Actuator or components are stationary or creeping slowly.) 2. Plugged inlet filter element. 2. Replace filter element. Poor response. (Servovalve output lags Partially plugged filter element. Replace filter element and check for dirty electrical command signal). hydraulic fluid in system. Output flow obtained from one control 1. Plugged inlet orifices. 1. Return to factory. port only. (Actuator is hardover, or 2. Plugged inlet filter element. 2. Replace filter element. hydraulic motor is rapidly rotating. No 3. Plugged hydraulic amplifier assembly. 3. Return to factory. response to electrical command signal.) 4. Jammed spool. 4. Return to factory. Low flow gain. (Failure to meet high rate or Shorted coil assembly. Return to factory. rapid traverse speeds.) High threshold. (Jerky, possible oscillatory “Sticky” spool Return to factory. or “hunting” motion in closed loop system.) High Null Bias. (High input current required 1. Incorrect null adjustment 1. Readjust null to maintain hydraulic cylinder or motor 2. Partially plugged inlet orifice assembly. 2. Return to factory. stationary.) 3. Partially plugged filter element. 3. Replace filter element and check for dirty hydraulic fluid in system. 4. Partially plugged nozzle. 4. Return to factory. Table 1. Replacement Parts Figure 3 Part Description Qty. Part Number (G)72K Series Filter Replacement Kit 1 B52555RK099K001 Base O-Rings 4 -42082-040 Filter Plug Base O-Ring (X-Port) 1 -42082-013 Field Filter Housing O-Rings (I) 2 -42082-039 Replaceable Field Replaceable Inlet Orifice Filter Assembly Filter Internal O-Ring (I) 1 -42082-013 Filter Plug O-Rings (I) 2 -42082-060 Inlet Orifice O-Rings (I) 2 -42082-059 Pilot Stage Filter Tube (I) 1 -23020 Field Replaceable Filter (I) 1 -22050 Filter Housing O-Rings Filter Tube Motor Cap Gasket (I) 1 -24509 (I) Included in Filter Replacement Kit. 10. FIELD REPLACEABLE FILTER ASSEMBLY REPLACEMENT 12. AUTHORIZED REPAIR FACILITIES a. Remove four socket head cap screws and lockwashers on filter cover using If servovalve continues to malfunction after all recommended corrective 3 1 a /16 inch Allen wrench. Remove filter cover plate. Use /4-28 screw to pull action procedures are performed, defective valve should be returned to Moog for repair. Moog does not authorize any facilities other than Moog or Moog filter plug out. subsidiaries to repair its servovalves. It is recommended you contact Moog at b. Remove o-rings and old filter from filter plug. (716) 652-2000 to locate your closest Moog repair facility. Repair by an c. Inspect filter for foreign material and discard. independent (unauthorized) repair house will result in voiding the Moog d. Install o-rings on filter plug and inside new filter. warranty and could lead to performance degradation or safety problems. e. Install filter, filter plug and cover plate. Torque screws to 85 inch-pounds. 13. DECLARATION OF MANUFACTURER 11. FUNCTIONAL CHECKOUT AND CENTERING An EC Declaration of Conformity according to Council Directive a. Install servovalve on hydraulic system or test fixture, but do not connect 94/9/EC is supplied with each servovalve. electrical lead. b. Apply required system pressure to servovalve and visually examine for evi- dence of external leakage. If leakage is present and cannot be rectified by replacing o-rings, remove the discrepant component and return for repair or replacement. Note: If the system components are drifting or hardover, adjust the mechanical null of the servovalve. c. Connect electrical lead to servovalve and check phasing in accordance with system requirements. 2 (G)72K SERIES INSTALLATION AND OPERATION INSTRUCTION NOTES 1 Fluid: Industrial type petroleum base hydraulic 3.62 MAX fluid, maintained to ISO DIS 4406 Code [92.0] 1.81 14/11 recommended. [46.0] 2.875 [73.03] 1.437 4 MOUNTING HOLES 2 OperatingTemperature Range: [36.50] .406 [10.31] THRU -40˚F to 275˚F [-40˚C to 135˚C] unless 2.03 otherwise specified on nameplate. 1.687 [51.6] [42.85] 4.06 [103.1] 3.375 [85.73] 3 Valve Phasing: 3.05 Flow out port B results when Series [77.5] coils: B & C connected,A+, D-; Parallel coils:A & C connected, B & D FIELD REPLACEABLE connected; Single coil:A+, B-, or C+, D-. .86 2.26 FIRST STAGE FILTER [22.0] [57.4] 1.73 [43.9] 4 Surface: PIN D PIN A Surface to which valve is mounted 5.15 [130.8] 63 PIN C requires [ ] finish, flat within .002 PIN B OPTIONAL 2.24 MAGNETIC [56.9] [0.05] TIR. MECHANICAL NULL ADJUST 5 NULL ADJUST 5 Null Adjust: Flow out port B results with clockwise 3 3.28 rotation of null adjust screw ( /32 hex key). 1.37 2.75 [83.3] 2.38 [60.5] [34.8] 4.48 [69.9] DIA TYP [113.8] 3.69 6 Ports: MAX 1.50 [93.7] [38.1] P, R,A & B: 0.625 [18.88] Diam. port O- PRESS Rings: 0.070 [1.78] section x 0.801 LOCATING PIN .28 6.70 .25 [6.4] [20.34] I.D. (universal size -019). [7.1] [170.2] Valves are supplied for either internal or external pressurization of pilot stage through Auxiliary Port:Aux. Port Diam; 0.213 [5.41].Aux. Port O-Ring: 0.070 [1.78] section x 0.364 [9.25] I.D. (universal size -012). 4.250 4X .375-16 UNC-2B THD RETURN PORT 2.125 M .013 4X .397 THRU 2.000 .593 .60 .014 M 1.000 CONTROL PORT A TYPICAL WIRING SCHEMATIC 2.125 1.687 1.000 5.00 3.375 2.000 .750 4.250 1.500 1.500 AB C D 2.50 3 .39 .30 .014 M CONTROL PORT B .750 VALVE MOUNTS 1.437 1.60 4X .688 ON THIS MANIFOLD .014 M SURFACE 2.875 PRESSURE PORT .250 AUXILIARY PILOT PORT PER SAE J1926 PRESSURE PORT .4375-20 UNF-2B 63 DASH 4 STR THD O-RING .014 M 2.50 .0015 BOSS (.25 TUBE OD REF) 1.25 4X PORT PER SAE J1926 4 4 PL 1.625-12 UN-2B DASH 20 STR THD O-RING 2.50 BOSS (1.25 TUBE OD REF) P Figure 4 5.00 The products described herein are subject to change at any time without notice, including, but not limited to, product features, specifications, and designs. Moog Inc., East Aurora, NY 14052-0018 Telephone: 716/652-2000 Fax: 716/687-7910 Toll Free: 1-800-272-MOOG www.moog.com CDS6754 RevB 500-448 1209 ∆∆