Reduced bore, EN558/s.1, AISI 304 fittings, EPDM WRAS rubber, 300µm blue EP

Anthony Whittam AVK UK Network Water Specialist

Anthony Whittam

Network Water Specialist

Control valve, pressure sustaining/relief, for drinking water or other neutral liquids to max. 70°C. The series offer two ranges, reduced bore and full bore. The reduced bore has reduced capacity compared to the full bore. For further info on the full bore see separate datasheet 879/101X99-001.

AVK series 879 diaphragm actuated pressure sustaining control valves (PSV) automatically secure a minimum upstream pressure by reducing the flow if the upstream pressure drops below the setpoint.

Adjusting the setpoint above the usual operating pressure changes the function to pressure relief (PRV), where the valve automatically opens to dump excess upstream pressure if it exceeds the setpoint.

A replaceable spring inside the pilot makes it possible to operate in different pressure ranges and still keep the high precision. Setting and adjustment on a control knob on the pilot.

Both full bore and reduced bore versions are available with the full bore having full capacity and the reduced bore having increased precision and smooth regulation at low flow rates.

Variant 879/001X99-001
Connection: Flanged
Material: Ductile Iron
PN: PN 10/16


  • The lifted seat design controls the flow around the plug so that in case of cavitation this happens with minimal damage away from plug and seat
  • The parabolic shape of the plug creates a smooth regulating characteristic with low gain around the near-closed positions improving control performance at low flow
  • Non-symmetric axial position of rubber diaphragm results in low stretch stress when closed
  • Body and bonnet of ductile iron coated with fusion bonded epoxy, 300µm, GSK approved, RAL 5017, according to DIN 3476 and WRAS-DVGW/W270/UBA
  • All rubber parts approved for drinking water
  • All non-coated internals made of stainless steel or bronze
  • Seat and pilot in stainless steel AISI 304
  • A needle valve fitted between the upstream side and the control chamber allows for adjustment of the regulation reaction time
  • Closing the needle valve isolates the control chamber and fixes the position of the main valve allowing for service of the pilot valve
  • Fittings, pipes and accessories in Ni-plated brass


Installation, Operation & Maintenance
Related Datasheets
Tender Text


1. Body Ductile iron GJS-500-7
2. O-ring EPDM
3. O-ring EPDM
4. Plug sealing EPDM
5. Hex Nut Stainless steel A2
6. Washer Stainless steel 304
7. Bolts Stainless steel A2
8. Diaphragm EPDM
9. Spring Stainless steel 304
10. Flat Seal EPDM
11. Flat Seal EPDM
12. Cover Ductile iron GJS-500-7
13. Hex Nut Stainless steel A2
14. Diaphragm Support Ductile iron GJS-500-7
15. Obturator Ductile iron GJS-500-7
16. Regulating Plug Stainless steel 304
17. Seat Stainless steel 304
18. Stem Stainless steel 304
19. Pilot valve Stainless steel
20. Pressure gauge Stainless steel
21. Ball valve
22. Needle valve Stainless steel


  • Hydraulic test: 1.5 x PN |
  • Tested according to EN12266-1. Seat: 1.1 x PN (in Bar), Body: 1.5 x PN (in Bar)


  • Designed according to EN 1074 - 5
  • Face to face according to EN558 Table 2 Basic Series 1
  • Standard flange drilling to EN1092 (ISO 7005-2), PN 10/16
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