2
Description continued,
Any process leakage passing through the
packing is permitted to escape through a leakoff
vent which passes through the packing box and
out the valve body. This prevents any leakage
from passing along the stem into the actuator
and also prevents loading pressure leakage
from the lower diaphragm from reaching the
valve body through the stem.
Table 1: Specifications
Factory-set specifications for your individual CVS 128PQC Control Valve are stamped on the
nameplate, located on the upper diaphragm casing.
End Connection Style
CVS Type 128 PQC
1-inch NPT Female
Port Diameters
CVS Type
128PQC
Metal Seat
In
1/4, 3/8, 1/2
mm
6.4, 9.5, 12.7
Soft Seat
In
1/4, 3/8, 1/2
mm
6.4, 9.5, 12.7
Maximum Inlet Pressures and
Temperatures**
-20
o
F to +100
o
F (-29
o
C to 38
o
C)
3600 psig (248 bar)
+150
o
F (+66
o
C)
3550 psig (245 bar)
+180
o
F (+82
o
C)
3520 psig (243 bar)
Maximum Pressure Drops**
See Table 2
Actuator Operating Pressures
20 psig (1.4 bar) or 35 psig (2.4 bar)
Maximum Actuator Casing
Pressure
100 psig (6.9 bar)
Shutoff Classifications
Metal Seat
ASME Class IV ASME/FCI 70-2-1998
– 0.01 percent of
maximum valve capacity using air at a pressure drop of 50 psi
(3.4 bar, differential), at 50
o
F to 125
o
F (10
o
C to 52
o
C)
Soft Seat
ASME Class IV ASME/FCI 70-2-1998
– Less than one bubble
per minute (0.15 ml) per minute using air at a pressure drop of
50 psi (3.4 bar, differential) at 50
o
F to 125
o
F (10
o
C to 52
o
C)
Material Temperature
Capabilities
Metal Seat
-20
o
F to +180
o
F (-29
o
C to +82
o
C)
Soft Seat
-20
o
F to +150
o
F (-29
o
C to +55
o
C)
Flow Characteristic
Quick opening with 45-degree taper valve plug
Flow Direction
Either direction
Maximum Rated Travel
3/8 inches (10mm)
Actuator Diaphragm Effective
Area
33 inches
2
(213 cm
2
)
Actuator Pressure Connection
1/4-inch NPT Female
Valve Travel Indication
Valve travel is indicated on plastic indicator cover with scale divisions indicated every 25 percent
of travel.
Approximate Weight
CVS Type 128 PQC
17 lb (7.7 kg)
** Pressure and temperature restrictions outlined in this guide, along with any applicable code limitation, should not be exceeded
Warning:
The leakoff vent must be kept open at all
times. Flammable or other hazardous fluids
should be vented into an open, well-ventilated
area to prevent fire or explosion.