How to Replace a Rubber Cup Diaphragm on a Gauge Protector

How to Change a
Rubber Cup Diaphragm in
a Gauge Protector
https://www.DrillingInstruments.com

Important Safety Notice
Proper service and repair is important to the safe and reliable operation of all Crown Oilfield Instrumentation equipment. The service
procedures recommended by Crown Oilfield Instrumentation and described in the service guide are recommended methods of
performing service operations. Some of these service operations require the use of tools specially designed for their purposes. These
special tools should be used when and as recommended.
It is important to note that some warnings against the use of specific service methods stated in the guide can damage the equipment or
render them unsafe. It is also important to understand these warnings are not exclusive. Crown Oilfield Instrumentation could not
possibly know, evaluate and advise service personnel of all conceivable methods in which service might be done or of the possible
hazardous consequences which may occur. Accordingly, anyone who uses service procedures or tools, which are not recommended by
Crown Oilfield Instrumentation, must first thoroughly satisfy himself that neither his safety nor equipment safety will be jeopardized by
the method selected.
The 1502 gauge protector(CD106) comes with rubber cup diaphragm (CD200). The CD200 protects the
gauge internals from harsh drilling fluids and senses pressure to transmit it to the gauge. When the rubber
cup becomes worn, damaged, or blown, it will need to be replaced. Follow these steps to replace your
1502 gauge protector rubber cup diaphragm.
How to Change a Rubber Cup Diaphragm

What You‘ll Need:
1. Needle Nose Pliers
2. Retainer Nut (CN101)
3. Screwdriver
4. Diaphragm Cup (CD200)
5. Retainer Nut Wrench (CW109)
6. Diaphragm Protector (CD106)
1 2 3 4 65

Step One
Turn gauge protector (CD106) over, and place
it in a vice so that the retainer nut is
exposed. The vise will grip the top of the
gauge protector’s housing with the base of
the device and the retainer nut exposed. As
shown, the hammer union (wing nut) is
still attached to the gauge protector.
Vise
Retainer Nut
(CN101)
Gauge
Protector
Housing
Hammer
Union

Step Two
The retainer nut is located at the bottom of
the gauge protector housing. Use retainer
nut wrench to loosen the retainer nut. By
turning the wrench to the left (counter-
clockwise), you will be able to remove the
retainer nut.
Retainer Nut
Wrench
(CW109)
Gauge Protector
Housing
Retainer
Nut
(CN101)
Click on picture to learn more about CN101.

Step Two Continued
Retainer Nut
(CN101) Being
Removed
Retainer Nut
Wrench (CW109)

Step Three
After the retainer nut is removed, the
diaphragm cup will be exposed sitting on a lip
within the gauge protector housing. Slip a
flat-head screwdriver between the rubber
cup and diaphragm housing wall. Using the
screwdriver, pry rubber cup diaphragm away
from the wall of the gauge protector housing.
Once there is a gap large enough, grab the
rubber cup lip with a pair of needle nose
pliers.
Gauge Protector
Housing
Rubber Cup
Being Pried Out
of Housing

Step Three continued
After prying the rubber cup off the wall, and
once there is a gap large enough, grab the
rubber cup lip with a pair of needle nose
pliers.
Gauge Protector
Housing
Rubber Cup
Being Pried Out
of Housing
Needle Nose and
Screwdriver Prying Cup
Away from Housing

Step Three Continued
Turn and pull on the rubber cup until it pulls free
of the diaphragm protector housing. Remove cup
from housing and inspect housing to make sure
that all parts of the rubber cup have been
removed.
Caution
Some diaphragm cups will shred or tear from use
or when being removed. Be sure to remove all
parts of the old diaphragm cup so that the new
one will fit properly. Failure to do so could result in
inaccurate pressure readings or in small rubber
cup parts contaminating the fluid in gauge
internals.
Rubber
Cup Being
Removed

Step Four
Insert new rubber cup diaphragm into housing as
shown in the picture. Smaller, closed-in top goes
into housing first, with larger, rubber cup opening
going into housing last.
New Rubber Cup
Being Inserted into
Housing.
Click on picture to learn more about CD200.

Step Five
Use one of the handles of the retainer nut wrench
to push the diaphragm cup back into the housing.
Cup should fit back inside grove and will give a
slight pop when back in place.
Caution
Do not use anything sharp to push the rubber cup
into the housing. Doing so could puncture the cup,
decrease gauge accuracy and/or damage gauge
internals.
Retainer Nut Wrench Handle
Being Used to Push in
Rubber Cup.

Step Six
To keep retainer nut from cutting or tearing the
rubber cup diaphragm, grease retainer nut
threads and lip with silicon-based grease.
Silicon-based
Grease

Step Seven
Thread retainer nut until finger tight, then use
retainer nut wrench to tighten nut.
Caution
Retainer nut
threads may
be sharp.

Step Seven Continued
Retainer nut should be sitting
just below lip of gauge
protector housing, meaning
just below flush.
Caution
Overtightening retainer nut can
reduce gauge accuracy and/or
destroy rubber cup diaphragm.
Care should be taken to avoid
over tightening and/or
compressing the rubber cup.

For any questions not covered in this guide, contact Crown at
Phone: 1-877-908-3790
Email: sales@drillinginstruments.com

How to Replace a Rubber Cup Diaphragm on a Gauge Protector

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How to Replace a Rubber Cup Diaphragm on a Gauge Protector