Product description
The Mark 708 Series provides accurate control on fractional flow applications. It is a complete line of pneumatic and electrically actuated control valves designed to enhance performance to ensure precision control on your most critical micro flow applications. The valve is ideal on pilot plant installations, test standards, R & D facilities, processing plants and specialized processing plants (dosing, injection and venting).
Regelventil MK708
Size
- 1/4", 1/2", 3/4" (DN8, DN15, DN20)
End Connections
- Threaded – NPT, BSPT, BSPP
- Socket weld
- Integral tube ends (max Cv or 0.2 on 1/4" TN option)
- Welded flanges (ANSI, DIN, JIS)
- Others upon request (contact factory)
Actuators
- 1/4" (DN8) – standard: 14M (14 in2) multi-spring
- 1/2" (DN15) – standard: 14M
- 3/4" (DN20) – standard: 14M; optional 35M (35 in2)
Diaphragm
- 14M – rolling (Nylon/Nitrile)
- Optional 35M Actuator: Buna-N fabric reinforced
Body/Bonnet Material
- Carbon Steel
- Stainless Steel
- Hastelloy C
- Hastelloy B
- Alloy 20
- Monel
- Titanium
- Other materials upon request
Trim Material
- Cv's 0.05 (0,04 Kv) and above: 17-4 plug, 316SS stem/seat
- Cv's below 0.05 (0,04 Kv): Nitronic 60 stem/plug & seat
Optional Trim Materials
- 316SS Stem, 17-4 plug, 416SS seat
- 316SS Stem, Stellite plug and Stellite seat (hard seat only)
- 316SS Stem/plug & seat
- 316SS Stem plug, PEEK 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 mate-rial 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
- 3-15 or 6-30 psi (0,21-1,0 or 0,4-2,1 bar) split ranges are available with optional positioner
Action
- Direct (air signal closes valve)
- Reverse (air signal opens valve)
Flow Characteristics
- Linear (all Cv's), equal percentage (Cv >/= 0.05/0,43 Kv only); or quick opening (Cv >/= 0.05/0,43 Kv only
Features and Benefits
- 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.
- 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 450°F (232°C), while braided or Graphite/Grafoil may be used for higher temperature requirements
- The bolting provides solid construction and secure connection. This bolting adds ease to maintenance, as bonnet/actuator assembly may be removed from the valve body in-line.
- The 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)
- The secondary stem connection eliminates stroke adjustment when changing trim facilitating faster, easier trim changes (not applicable to cv’s below 0.05).
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