Parr Instrument A238VB User Manual

626M

A238VB Valve

Operation and Maintenance Instruction Manual

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.

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.

6. Remove the lantern ring.

7. Remove the valve seat and discard.

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A238VB Valve

BAR HANDLE

233VB

234VB2*

VALVE NEEDLE

235VB

PACKING NUT

7VBCM

WASHER, MONEL

2X 4VB3

PTFE PACKING

SEE NOTE 2

21VB*

LANTERN RING

20VBHB

VALVE SEAT

237VB*

VALVE BODY

1/8NPTM X 1/8NPTF

Notes:

1. * Indicates parts required in special material

2. Substitute (1) 4VB4KL grafoil packing for high-temp

3. Optional fittings for outlet 280VB* nipple 1/8NPTM × 1/8NPTM

or A92HW* male connector 1/8NPTM × 1/4TUBE

A238VB Valve

Revision 07/11/13

P

arr Instrument Company

211 53rd Street • Moline, Illinois 61265 USA 1-309-762-7716 • 1-800-872-7720 • Fax: [phone]

E-mail: [e-mail] • http://www.parrinst.com