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1. Description 

 
The LF-690 is a single stage piston sensed pressure regulator, capable of a maximum 690 bar 
inlet pressure.  This  can then  be  controlled to  a range  of  outlet pressures  depending  upon 
the  sensing  arrangement.  As  standard,  the  LF-690  comes  with  a  Tungsten  Carbide  main 
valve  and  heat  treated  17-4ph  seat,  which  provides  excellent  resistance  to  erosion  on 
hydraulic media.  
 
Ceramic  Ball  and  Plug  options  are  available  which  provide  ultimate  protection  against  the 
harsh service encountered on hydraulic systems with the Ceramic Plug design allowing the 
LF-691 to achieve up to 1380 bar inlet*. 
 
The regulator is also available with balanced main valve options which allow high accuracy 
control of both low and high downstream pressures. 
 
The housing has been machined from 316 SS (17-4ph SS on the LF-691 high pressure option) 
to  ensure  maximum  protection  against  the  media  on  which  it  will  be  used,  and  the 
environment in which it will be placed. 
 
*achievable with specific modification 

 Please contact the office for information. 

 

2. Installation 

 
Before system start-up, it is recommended that all systems be pressure tested, leak tested 
and purged with an inert gas such as nitrogen. 

 

Prior to placing into service ensure that the regulator is in the fully closed position, with the 
adjusting mechanism turned completely anti-clockwise. 
 
Check  the  model  number  reference  to  ensure  that  the  pressure  range  complies  with  the 
installation requirements.  
 
Visually  inspect  the  regulator  for  any  signs  of  damage  or  contamination.  If  any  foreign 
materials are present and cannot be removed from the regulator, or if the threads on the 
regulator appear to be damaged, please contact the office immediately to  arrange for the 
regulator to be returned for service. 
 
The Inlet and Outlet ports are clearly marked. Select the correct size and type of connection 
fittings  for  these  ports  which  are  indicated  in  the  regulators  part  number.  Both  medium 
pressure  type  (MP) 

‘A’ 

and  National  Pipe  Thread  (NPT) 

N

  options  are  available  on  this 

regulator.  For  NPT  threads,  ensure  that  PTFE  tape  is  applied  correctly  to  the  fittings, 
applying two overlapping layers in the direction of the thread, taking care that the tape does 
not come into contact with the first thread.  
 

Any gauge ports on the regulator will be 1/4” NPT unless otherwise stated. If any gauge port 

is not required, ensure that the port is plugged prior to installation.  
 

Summary of Contents for LF-690

Page 1: ...1 THE LF 690 691 SERIES Operating and Service Manual Series includes all variants of LF 690 691 Issue D March 2020...

Page 2: ...F 690 with Domed SA Unbalanced MVA 8 6 2 Servicing the LF 690 Balanced Regulator 9 6 2 1 Accessing the Balanced Main Valve Assembly MVA 9 6 2 2 Figure 2 Sectional View of the LF 690 Balanced MVA 10 6...

Page 3: ...systems be pressure tested leak tested and purged with an inert gas such as nitrogen Prior to placing into service ensure that the regulator is in the fully closed position with the adjusting mechanis...

Page 4: ...ny time The LF 690 series may be offered with pressure limiting pressure locking or pre set pressure options Pressure limited regulators are fitted with locknuts on the adjusting mechanism in order to...

Page 5: ...office Servicing and maintenance work on the LF 690 regulators should only be performed after fully reading and understanding the Operating and Servicing Manual Due to the compressibility of gases the...

Page 6: ...eplace the connector pin chamfer down into the body while the body is up side down The pin should locate within the baffle plate 3 vi The new ceramic seat 2 should be placed in the seat cartridge 5 wi...

Page 7: ...ing the sensor firmly in a vice with the vent seat nut 13 facing upwards ix The vent seat nut 13 can be removed using a 10mm open ended spanner and the vent seat 14 can then be removed from the sensor...

Page 8: ...13 PT C 091 VENT SEAT NUT 14 PT C 029 013 PEEK VENT SEAT 15 PT C 042 LOAD SPRING 16 PT C 045 ADJUSTING NUT 17 PT C 046 SCREW 18 PT C 043 004 ADJUSTING SCREW 19 BEAR 51103 SS SS BEARING 20 FIT M3x6MM S...

Page 9: ...does not fall out of place viii Replace all of the O rings and Backups 31 34 38 39 40 within and around Bottom Nut 3 Note The small back up ring 38 should be placed into the bottom nut 3 first followe...

Page 10: ...10 6 2 2 Figure 2 Sectional View of the LF 690 Balanced MVA...

Page 11: ...vent seat 23 for damage and replace xi Replace all O rings and backups 29 30 33 35 37 located on the sensor 15 and sensor holder 14 prior to reassembly ensuring adequate lubrication is used xii Inser...

Page 12: ...087 12mm SENSOR 16 PT C 091 VENT SEAT NUT 17 PT C 042 MAIN LOAD SPRING 500KG 18 PT C 040 BONNET 19 PT C 043 004 ADJUSTING SCREW 20 PT C 045 ADJUSTING NUT 21 PT C 046 ADJUSTING NUT SCREW 22 BEAR 51103...

Page 13: ...the connector pin chamfer down into the body while the body is up side down The pin should locate within the baffle plate 3 vi The new ceramic seat 2 should be placed in the seat cartridge 5 with the...

Page 14: ...s vii The vent seat nut 13 can be removed using a 10mm open ended spanner and the vent seat 14 can then be removed from the sensor 10 along with the 6 85mm x 2mm O ring 22 viii Inspect the vent seat 1...

Page 15: ...HOLDER 12 PT C 095 001 DOMED SPRING REST 13 PT C 091 003 VENT SEAT NUT 14 PT C 029 013 001 PEEK VENT SEAT 15 SPR G40X89 LOAD SPRING 16 PT C 045 ADJUSTING NUT 17 PT C 046 SCREW 18 PT C 043 001 ADJUSTI...

Page 16: ...perating Temperature 20 C to 80 C Materials Body and Trim 316 SS Seat Ceramic Flow Capacity Cv Standard 0 1 High Pressure 0 05 Balanced 0 3 Leakage Liquid Zero drops of water at max inlet Gas Bubble t...

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