Data Sheet

Bulletin 71.1:MR105
9
PART NAME STANDARD OPTIONAL
Body WCC steel
(1)
Cast Iron, CF8M, CF3M Stainless steel
Body Flange WCC steel
(1)
CF8M, CF3M Stainless steel
Actuator Casings - Low Pressure AISI 1010 steel
(1)
316/316L Stainless steel
Actuator Casings - High Pressure WCC steel
(1)
CF3M/CF8M Stainless steel
Internal Stiffener Plate AISI 1010 steel
(1)
316/316L Stainless steel
Spring Case WCC steel CF3M/CF8M Stainless steel
Spring Case Spacer Zinc-Plated steel Stainless steel
Cage CF3M/CF8M (Quick Opening), CF8M (Linear) Stainless Steel
Valve Plug and Seat Ring 416 Stainless steel
316, 316L,
S20910 (Nitronic 50) Stainless steel
(NPS 1 / DN 25 body size only)
Closing Spring Inconel
®
X750
Stem S17400 H1075 Stainless steel S20910 (Nitronic 50) Stainless steel
Lower Diaphragm Support S17400 H1075 Stainless steel
Diaphragm and Seals Nitrile (NBR) Fluorocarbon (FKM), Ethylene Propylene (EPDM)
Upper Diaphragm Plate Cast Iron
Control/Set Spring Steel Alloy
(1)
Spring Seats Zinc-Plated steel
Bolting
SA194 Grade B7/NCF (Body to Bonnet),
SAE Grade 5/NCF (Actuator)
Stainless steel
Adjusting Screw Zinc-Plated steel Stainless steel
1. Powder coated.
Table 6. Construction Materials
where,
Q = gas ow rate, SCFH
G = specic gravity of the gas
T = absolute temperature of gas
at inlet, °Rankine
C
g
= gas sizing coefcient
P
1
= absolute inlet pressure, psia
C
1
= ow coefcient
ΔP = pressure drop across the regulator, psi
Then, if capacity is desired in normal cubic meters per hour
at 0°C and 1.01325 bar, multiply SCFH by 0.0268.
Liquid Capacities
To determine regulating capacities or to determine
wide-open capacities for relief sizing at any inlet
pressure, use the following equation.
Q = C
v
ΔP
G
where,
Q = liquid ow rate, GPM
ΔP = pressure drop across the regulator, psi
C
V
= regulating or wide-open ow coefcient
G = specic gravity of the liquid
Maximum Allowable Pressure Drop for Liquid
Pressure drops in excess of allowable will result in
choked ow and possible cavitation damage.
Choked ow is the formation of vapor bubbles in
the liquid owstream causing a condition at the
vena contracta which tends to limit ow through
the regulator. The vena contracta is the minimum
cross-sectional area of the ow stream occurring just
downstream of the actual physical restriction.
Cavitation and ashing are physical changes in the
process uid. The change is from the liquid state to
the vapor state and results from the increase in uid
velocity at or just downstream of the greatest ow
restriction, normally the regulator orice.
To determine the maximum allowable pressure drop
for water:
ΔP
(allow)
= Km (P
1
)
where,
ΔP = Valve differential in psi
K
m
= Valve recovery coefcient from Table 5
P
1
= Valve inlet pressure in psia
Inconel
®
is a mark owned by Special Metals Corporation.