MIL-PRF-24790A (SH)
APPENDIX
A
COMPRESSION PACKING MATERIAL DYNAMIC LABORATORY TEST PROCEDURE
FOR FRESH WATER ROTARY AND PUMP APPLICATIONS AND
SATURATED LOW PRESSURE RECIPROCATING PUMP APPLICATIONS
A.1 SCOPE
A.1.1 Scope. This appendix details the laboratory performance tests (rotary and reciprocating) which are
designed to determine if non-asbestos compression packing materials are capable of achieving and maintaining a
proper seal in a simulated environment which meets operational safety requirements for naval applications. The
tests outlined herein are intended to qualify rotary pump packings (Type I, Class A) for hot water applications, and
reciprocating pump packings (Type II, Class A) for saturated low-pressure steam applications. This appendix is a
mandatory part of the specification. The information contained herein is intended for compliance.
A.2 APPLICABLE DOCUMENTS
This section is not applicable to this appendix.
A.3 TESTING
A.3.1 Materials. The following tests shall be performed on non-asbestos compression packing materials
according to their recommended use and temperature/ pressure limitations. Three-eighths-inch square packing
material shall be specified for each test.
A.3.2 Conditioning. No preconditioning of materials shall be performed. It is desirable that the non-
asbestos compression material be exposed to existing environmental conditions, as would be expected in supply
storage aboard a naval vessel.
A.3.3 Test procedures for Type I, Class A rotary pump packings for fresh water applications. A rotary pump
test device is required and shall be in accordance with figure A-1. This device shall have variable shaft speeds up
to 4000 fpm. The surface finish and straightness of the test shafting shall be of commercial pump grade.
A recirculating loop is required, preferably with an expansion tank in the loop. A heater and pressurizing
device are required to provide temperatures up to 250ºF and differential pressures across the packing of up to 150
psid. The test device shall have the capability of supplying the necessary fluids for exposure to the packing
material. It shall have provisions for measuring the test fixture shaft surface temperature in the area of the second
ring of packing (counting from the outside ring). The test device shall be configured to permit data acquisition
(shaft temperature, pressure and temperature of the fluid) at intervals of 30 seconds or less, and shall have
provisions for collecting extruded packing material.
A.3.3.1 Test media, pressures, temperatures, and leakage rates. The following test conditions shall be
provided (To qualify, packings shall complete the test successfully under both conditions):
Media
Pressure Temperature
Shaft speed
No. of packing rings
Water
150 psid
250ºF
4000 fpm
5
Water
150 psid
250ºF
2100 fpm
4
Maximum allowable value of average overall leakage rate shall be as follows:
300 mL per minute @ 4000 fpm.
60 mL per minute @ 2100 fpm.
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