Mark 708 Series Low Flow Pneumatic Control Valve

Brand: LowFlow Valve

The Mark 708 was developed by Jordan Valve to provide the most accurate control available for fractional flow services: whether for pilot plant installation, test stands, R & D facilities, or for specialized processes such as dosing, injection and venting applications.

With Cv's ranging from 0.00001 to 4.0 available in 1/4" through 1" lines sizes (0,000009 to 3, 4 Kv in sizes DN8 through DN20), the Mark 708 offers design features that will provide enhanced performance to insure precision control on your most critical micro-flow flow applications.

The Mark 708 Series is a complete line of pneumatic and electric control valves developed specifically for the unique properties and conditions encountered in fractional flow services.

The 708 Series comes standard with the quick change option - for applications requiring frequent trim changes without disturbing the actuator setting.
Features
  • Rolling diaphragm - the rolling diaphragm design ensures that the effective diaphragm area remains relatively constant, regardless of valve stem position. This increases accuracy of the actuator when positioning the valve by ensuring a linear response to input signal changes.
  • Spring-loaded TFE/Chevron packing - the spring-loaded packing maintains a proper compression, while minimizing excessive friction. This alleviates the need for most field adjusting. The TFE packing is suitable for temperatures to 450ºF (232ºC), while braided or Graphite/Grafoil may be used for higher temperature requirements.
  • Bolted body/bonnet connection - the bolting provides solid construction and secure connection. This bolting adds ease to maintenance, as bonnet/actuatorassembly may be removed with a valve body in-line.
  • Guided trim - extended orifice and plug guiding are standard and offers improved shutoff and accuracy equivalent to heavy duty trim option of competitors (not applicable to cv's below 0.05).
  • Quick change trim - the secondary stem connection eliminates stroke adjustment when changing trim facilitating faster, easier trim changes (not applicable to cv's below 0.05).

Specifications

Sizes

  • 1/4" (DN8)
  • 1" (DN25)
  • 3/4" (DN20)
  • 1/2" (DN15)

End Connections

  • Others upon request (contact factory)
  • Welded Flanges (ANSI, DIN, JIS)
  • Integral Tube Ends (max Cv or 0.2 on 1/4" TN option)
  • Socket Weld
  • Threaded - NPT, BSPT, BSPP

Actuator

  • 1" (DN25) - standard: 35M
  • 3/4" (DN20) - standard: 14M; optional 35M (35 in^2)
  • 1/2" (DN15) - standard: 14M
  • 1/4" (DN8) - standard: 14M (14 in^2) multi-spring

Diaphragm Material

  • 14M - rolling (Nylon/Nitrile)
  • Optional 35M Actuator: Buna-N fabric reinforced

Body / Bonnet Materials

  • Other materials upon request
  • Titanium
  • Monel
  • Alloy 20
  • Hastelloy B
  • Hastelloy C
  • Stainless Steel
  • Carbon Steel

Trim Materials

  • Cv's below 0.05 (0,04 Kv): Nitronic 60 stem/plug & seat
  • Cv's 0.05 (0,04 Kv) and above: 17-4 stem/plug, 316SS seat

Optional Trim Materials

  • 316SS Stem plug, PEEK seat
  • 316Ss Stem/plug & seat
  • 316SS Stem, Stellite plug and Stellite seat (hard seat only)
  • 316SS Stem, 17-4 plug. 416SS seat

Actuator Materials

  • Aluminum - 14M
  • Steel - 35M

Stem Packing

  • Standard: spring-loaded TFE/Chevron (to 450°F/232°C)
  • Optional: braided or Graphite/Grafoil (with positioners on 14M)

Body / Bonnet Gasket

  • RPTFE or Grafoil (matches packing material unless specified)

Service

  • Steam
  • Air
  • Gas
  • Oil
  • Water
  • Chemicals

Shutoff

  • Standard - Cv's 0.05 and greater: ANSI Class IV; Cv's 0.02 and lower: ANSI Class VI
  • Optional - Cv's 0.05 and greater: ANSI Class VI (with PEEK seats)

Ranges

  • 3-5 or 6-30 psi (0,21-1,0 or 0,4-2,1 bar) split ranges are available with optional positioners

Action

  • Direct (air signal closes valve)
  • Reverse (air signal opens valve)

Flow Characteristic

  • linear (all Cv's), equal percentage (Cv >/= 0.05/0,43 Kv only); or quick opening (Cv >/= 0.05/0,43 Kv only)

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