Parr Instrument A238VB - Manual

A238VB Valve
Operation and Maintenance Instruction Manual
626M
Operation/Caution
The A238VB Series Valve has a soft seat seal.
Note: While this type of valve seals very
easily, they also have a tendency to be
“overtightened” when closing during
operation.
CAUTION: “Overtightening” will cause the
20VBHA Valve Seat to extrude into the valve
body, pinching off the orifice of the 20VBHA
Valve Seat. This may reduce flow through the
valve and the 20VBHA Valve Seat may need to
be replaced.
Dissasembly of the A238VB Series Valve
1. Fully open the valve by turning the bar
handle counter clockwise.
2. Loosen the packing nut by turning it counter
clockwise in relation to the valve body until
it’s threads are clear of the valve body.
3. Pull the handle, needle, and packing nut out
of the valve body together.
4. Remove the washer.
5. Remove the (2) PTFE packing or (1) Grafoil
packing. Inspect these parts for wear and
replace if necessary.
6. Remove the lantern ring.
7. Remove the valve seat and discard.
Assembly of the A238VB Series Valve
1. Before assembly, all parts should be clean
and in good condition.
2. Install the new valve seat into the valve
body.
3. Install the lantern ring.
4. Install the packing.
5. Install the washer.
6. Apply a small amount of molylube (Parr part
number 424HC) to the internal and external
threads of the packing nut.
7. With the valve needle still in the fully open
position, (threaded fully into the packing
nut) hand tighten the handle, needle, and
packing nut into the valve body.
8. When the packing nut has been installed
finger tight, tighten the packing nut with a
wrench an additional “three wrench flats”
(1/2 turn) to pre-load the packing.
9. Again note when closing, the valve should
not be overtightened.
P a r r I n s t r u m e n t C o m p a n y w w w . p a r r i n s t . c o m