Midland A-14150 Series Owner's manual

P/N: A-14150/A-14499, Rev. 1
Issue Date: February 8, 2021
Supersedes: April 28, 2017
External-Style Pressure Relief Valve
A-14150/A-14499 Series
Installation, Operation & Maintenance (IOM) Manual
Manual content is subject to change.
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A-14150/A-14499, Rev. 1
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Table of Contents
1!Regulations and Safety Requirements ...............................................................................................3!
!Regulations.................................................................................................................................. 3!1.1
!Safety Warnings and Precautions ...............................................................................................3!1.2
2!Introduction ......................................................................................................................................... 5!
!Valve Details................................................................................................................................ 5!2.1
3!Valve Installation................................................................................................................................. 7!
!Installation Procedure and Required Tools.................................................................................. 7!3.1
!Leak Inspection............................................................................................................................ 8!3.2
!Valve Operation Notes and Precautions...................................................................................... 8!3.3
4!Valve Qualification ..............................................................................................................................9!
!Valve Disassembly and Required Tools ...................................................................................... 9!4.1
!Component Inspection............................................................................................................... 14!4.2
!Valve Reassembly and Required Tools.....................................................................................21!4.3
!Testing Process .........................................................................................................................26!4.4
!Post-Test Final Assembly ..........................................................................................................28!4.5
5!Routine Maintenance........................................................................................................................30!

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1Regulations and Safety Requirements
Regulations1.1
Midland external-style pressure relief valves are used in contact with a variety of products, many of which are
hazardous materials and could cause serious injury or damage if mishandled. The acceptance and transportation of
products are regulated by the DOT and AAR in the U.S.A., and in Canada by CTC and Transport Canada. Regulations
of other governmental bodies must be complied with for stationary and mobile applications. All personnel should be
familiar with and follow these regulations. Nothing in these instructions is intended to conflict with or supersede these
regulations. The information in this document was gathered from knowledgeable sources. However, Midland
Manufacturing Corporation makes no representations or guarantees about its accuracy or completeness, and assumes
no liability for this information.
Specifications are subject to change without notice.
This valve should only be installed, operated and maintained by qualified personnel. Read all of these instructions
carefully before proceeding.
Operation of the valve must conform to all applicable specifications from TC, AAR, DOT, CFR (Parts 173.31, 174.67,
etc.) and other governmental bodies, along with the operating instructions of your company.
Safety Warnings and Precautions1.2
Please carefully read each of the following warnings and cautions prior to performing any work.
WARNING: Toxic Hazard. Always use extreme caution and proper equipment when involved with hazardous
materials. To avoid exposure to toxic or hazardous materials, make sure the tank car is empty and clean, and
that the work area is free of hazardous chemicals before removing or installing any valve.
•Wear protective clothing and equipment suitable for withstanding the materials to which you
may be exposed
•Position yourself on the upwind side of the valve when possible
•Work in a well-ventilated area
•Work with a partner who can help you in the event of an emergency
•Follow approved safety precautions for hazardous or toxic materials
•Obtain MSDS sheets for all the commodities used with the associated valve
WARNING: Spring-Loaded Assembly: These external-style pressure relief valves are spring-loaded
assemblies with a large amount of stored potential energy in the spring. Handle with care to avoid damage to the
valve stem, which could result in breakage and ejected piece parts.
When assembling or disassembling the valve, DO NOT position oneself directly in front of the spring and stem.
Instead, position oneself to the side away from the valve. Unexpected component failure of the valve stem or
spring breakage may cause a sudden energy release that can discharge component parts a short distance in an
uncontrolled manner. Personal injury may be a result.
WARNING: Spring-Loaded Assembly. During valve-spring disassembly, the valve contains springs under
load. DO NOT attempt to disassemble the valve without first reading these instructions or injury may result.
Spring pressure must be adjusted to the minimum and a bench clamp or press used for disassembly.
WARNING
WARNING
WARNING

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CAUTION: Valve Leakage. Improper valve-tongue seating in the flange groove, loose nuts and damaged
gaskets may result in leaks at the valve-mounting joint.
CAUTION: Incorrect Spring Setting. Never adjust the spring compression of a valve while it is mounted on the
vessel cover plate or incorrect settings may result.
CAUTION: Valve-Stem Eccentricity. Excessive valve-stem eccentricity will cause binding that can result in
high start-to-discharge pressure settings, reduced valve capacity and/or low vapor-tight pressures.
CAUTION: Valve-Stem Failure. Cracks and corrosion of pressure relief valve stems can result in stem failure
and uncontrolled venting.
CAUTION: Valve-Stem Straightening. Straightening of the stem by bending it in a press may result in the
buildup of uneven stresses in the stem, which may result in valve malfunction.
CAUTION: Valve-Spring Failure. Defects in coil springs, such as cracks and corrosion pits, can act as stress
concentrators. Failure to detect these defects can result in coil-spring breakage and uncontrolled valve venting.
CAUTION: Deficient Valve Travel. Coil springs that have taken a “set,” resulting in an undersized free-height,
will not allow the valve to open fully. The spring should not be bowed more than 1/4" when in the assembled
position. Bowing in excess of this amount can cause the spring to rub against the inside wall of the valve body
and adversely affect the pressure settings. If any of the defects mentioned above are observed, the spring
cannot be repaired and must be replaced.
CAUTION: Field Repair. The repair procedure for leaking valves in the field is intended only as a temporary
repair to get the car to an unloading destination. Once the product is unloaded and pressure is relieved, the
valve should be removed for a complete inspection and requalification.
CAUTION: O-Ring Replacement. Conducting this procedure may be hazardous (depending on the commodity
in the tank car). Maintenance personnel should be carefully trained before being permitted to perform the
procedure below on a pressure relief valve mounted on a pressurized tank.
CAUTION
CAUTION
CAUTION
CAUTION
CAUTION
CAUTION
CAUTION
CAUTION
CAUTION

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2Introduction
The A-14150 through A-14499 Series External-Style Pressure Relief Valves are designed to operate at 150 to 495 psig
(depending on spring setting) with flow rates from 3,582 to 8,616 standard cubic feet per minute (scfm).
Valve Details2.1
ITEM
QTY.
PART NAME
A-14150 THRU A-14495 STAINLESS TRIM
A-14154 THRU A-14490 STAINLESS STEEL
MATERIAL
PART NUMBER
MATERIAL
PART NUMBER
1
1
TOP GUIDE
STEEL
14-101-CS
STAINLESS STEEL
14-101-SS
2
1
STEM
STAINLESS STEEL
14-2-SS
STAINLESS STEEL
14-2-SS
3
1
PLUG
STAINLESS STEEL
14-3-SS
STAINLESS STEEL
14-3-SS
4
1
BODY
STEEL
14-4-STD-CS
STAINLESS STEEL
14-4-STD-MO
5
1
OUTER SPRING
STAINLESS STEEL
SEE TABLE BELOW
STAINLESS STEEL
SEE TABLE BELOW
6
1
FOLLOWER
STEEL
14-6-CS
STAINLESS STEEL
14-6-SS
7
1
GUIDE
STAINLESS STEEL
14-7-SS
STAINLESS STEEL
14-7-SS
8
1
TOP NUT
STEEL
15-8-CS
STEEL (2)
15-8-CS
9
1
TOP GASKET
BUNA-N (2)
15-9-BN
BUNA N (2)
15-9-BN
10
1
SHAFT SEAL
TEFLON
17-10-TF
TEFLON
17-10-TF
11
1
ADJUSTING SCREW
STAINLESS STEEL
SEE TABLE BELOW
STAINLESS STEEL
SEE TABLE BELOW
12
1
SEAL RETAINER
STEEL
14-12-CS
STAINLESS STEEL
14-12-SS
13
1
INNER SPRING
STAINLESS STEEL
SEE TABLE BELOW
STAINLESS STEEL
SEE TABLE BELOW
14
1
CAP
STAINLESS STEEL
14-14-SS
STAINLESS STEEL
14-14-SS
15
1
HEX HEAD CAP SCREW
STEEL
15-15-CS
STEEL (2)
15-15-CS
16
4
STUD (1)
STEEL
14-16-CS
STAINLESS STEEL
14-16-SS
17
4
NUT (1)
STEEL
14-17-CS
STAINLESS STEEL
14-17-SS
18
1
WIRE SEAL
SS WIRE, LEAD SEAL
22-72-PB
SS WIRE, LEAD SEAL
22-72-PB
19
1
RETAINER
STAINLES STEEL
14-19-SS
STAINLESS STEEL
14-19-SS
20
1
SEAT O-RING
BUNA-N (2)
10-10-BN
BUNA-N (2)
10-10-BN
21
1
PLUG O-RING
BUNA-N (2)
10-11-BN
BUNA-N (2)
10-11-BN
22
1
FLUE O-RING (3)
BUNA-N (2)
14-22-BN
BUNA-N (2)
14-22-BN
23
1
FLUE (3)
PLASTIC
14-24-PC
PLASTIC
14-24-PC
24
1
NAMEPLATE
STAINLESS STEEL
SEE TABLE BELOW
STAINLESS STEEL
SEE TABLE BELOW
25
1
PROTECTIVE CAP
W/CHAIN (3)
POLYETHLENE/SS
14-31-PE
POLYETHYLENE/SS
14-31-PE
Table 2-1 Valve Components – A-14150/A-14495 Series
NOTES:
(1) Valves with pressure settings less than 225 psig have bolts (15-16-CS or –SS) instead of studs and nuts.
(2) Alternate materials available.
(3) Optional. Add model number suffix –PF for plastic flue or –S for stainless flue. Items 22 & 25 are included.
VALVE MODEL
NO.
NAMEPLATE
VALVE
MODEL
NO.
NAMEPLATE
PRESSURE
SETTING (PSIG)
FLOW RATE
(SCFM AIR)
OUTER
SPRING P/N
INNER
SPRING P/N
ADJUSTING
SCREW P/N
A-14150
14-150-SS
A-14154
14-154-SS
150
3582
15-150-MO
14-13-SS
15-112-SS
A-14165
14-51-SS
A-14169
14-56-SS
165
3612
15-225-SS
–
15-11-SS
A-14225
14-36-SS
A-14229
14-43-SS
225
4629
15-150-MO
14-13-SS
15-11-SS
A-14247
14-52-SS
A-14251
14-57-SS
247.5
4766
15-300-SS
–
15-11-SS
A-14255
14-53-SS
A-14259
14-58-SS
255
4606
15-300-SS
–
15-11-SS
A-14280
14-54-SS
A-14284
14-59-SS
280.5
5177
15-225-SS
14-13-SS
15-11-SS
A-14300
14-37-SS
A-14304
14-304-SS
300
6024
15-300-SS
14-13-SS
15-11-SS
A-14330
14-55-SS
A-14334
14-60-SS
330
5085
15-300-SS
14-13-SS
15-11-SS
A-14375
14-38-SS
A-14379
14-45-SS
375
7299
15-375-SS
14-13-SS
15-111-SS
A-14450
14-39-SS
A-14454
14-46-SS
450
5971
15-450-SS
14-13-SS
15-111-SS
A-14495
14-51-SS
A-14499
14-53-SS
495
8616
15-450-SS
14-13-SS
15-111-SS
Table 2-2 Valve Technical Specifications – A-14150/A-14499 Series

A-14150/A-14499, Rev. 1
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Figure 2-1 Valve Component Identification

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3Valve Installation
New valves are tested, adjusted and sealed at Midland. If a new valve has been left in its original packaging, is
undamaged and is not more than six (6) months old, it may be installed on a tank car without retesting or recalibration.
Prior to installation, ensure that the valve remains clean and the gasket-sealing surfaces are not damaged.
Installation Procedure and Required Tools3.1
SAE Wrench
Component(s)/Description
1-1/4” Crow, Open-End or Socket Wrench
Mounting Bolts
Torque Wrench
Mounting Bolts
Other Tools, Supplies, and Equipment:
Wire Brush
Replacement Gasket
As Specified
Table 3-1 Required Tools for Valve Assembly
Remove the old valve and then insert a soft rubber plug into the tank opening to prevent debris from entering3.1.1
the tank during cleaning of the valve-mounting groove and studs on the manway cover plate.
Using a wire brush, brush the threads of the mounting studs to remove rust or scale. Nuts should move freely3.1.2
on clean studs. Studs should not exhibit excessive corrosion. Inspect threads for any sign of excessive wear,
corrosion, pitting or other defects. If any are found, the part is rejectable and should be replaced.
Remove and discard all used gasket material.3.1.3
CAUTION: Groove Damage. In order to avoid groove damage, do not scratch the metal in the bottom of
the groove when removing the old gasket.
Using a lint-free cloth and appropriate cleaning solvent, wipe clean the valve and cover-plate seating surfaces3.1.4
and the mounting-stud threads. Inspect threads for any sign of excessive wear, corrosion, pitting or other
defects. If any are found, the part is rejectable and should be replaced.
CAUTION

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Install the new gasket. Ensure it is fully seated. When a groove gasket is fully seated, 1/16" of free space3.1.5
should remain above the gasket to permit locating and entry of the valve tongue.
CAUTION: Do not use a sharp tool to press the new gasket into place or gasket damage may result.
Remove the rubber plug from the cover plate.3.1.6
Position the valve gently into the mounting. Align the body holes over the studs.3.1.7
Install the nuts and tighten them in 1/3-torque increments in a diagonally3.1.8
alternating sequence. Consult gasket manufacturer for recommended torque
requirements.
NOTICE: Consult gasket manufacturer and Midland Manufacturing for
torque requirements as max torque may vary by valve model. Do not
exceed 200 ft-lb.
NOTICE: This is for installation to the car, so the pattern is on the
outside bolts.
CAUTION: Uneven Gasket Compression. Do not over-tighten the
nuts on one side of the valve as this may tilt the valve and result in
uneven gasket compression.
TIP:Use a 1-1/4” wrench to tighten mounting nuts.
Figure 3-1 Tightening Sequence
Leak Inspection3.2
Test all newly installed valves to conform to car-owner specifications. No leaks should be present.3.2.1
Valve Operation Notes and Precautions3.3
CAUTION: Incorrect Setting. Never adjust the spring compression of a valve while it is mounted on the
vessel cover plate or incorrect settings may result.
NOTICE: Operation of the valve must conform to applicable TC, AAR DOT specifications (Parts 173.31,
174.67, etc.), other governmental bodies, and the operating instructions of your company.
CAUTION
NOTICE
NOTICE
CAUTION
CAUTION
NOTICE
1
2
3
4

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4Valve Qualification
NOTICE: To ensure best practice and consistency of your qualification procedure, O-rings, gaskets and
wire seals should always be replaced.
Nuts, washers and studs must be closely inspected before re-use or replaced regularly.
Valve components such as the top guide, stem, retainer, body, plug, follower and spring must be
thoroughly inspected.
Valve Disassembly and Required Tools4.1
SAE Wrenches
Component(s)/Description
Item #
7/16” Socket Wrench
Seat Screws
15
1-1/2” Wrench
Top Locknut
8
3/4” Wrench
Adjustment Screw
11
9/16” Socket Wrench
Top Guide Nuts
17
Other Tools, Supplies, and Equipment:
Wire Cutter
Seal Wire
18
Non-Scratching Tool
O-Rings
20, 21, 22
Table 4-1 Required Tools for Valve Disassembly
NOTICE: Valve disassembly should only be done by trained personnel with access to the proper
machines, tools, procedures and personal-protective equipment (PPE).
Remove the orange protective cap (item 25) and cut the rivet to release the4.1.1
cap chain.
Figure 4-1 Remove Cap and Seal
Wire
NOTICE
NOTICE
25
18

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Unscrew and remove the flue (tube) (item 23) from around the valve.4.1.2
Figure 4-2 Remove Flue (Tube)
Place valve assembly in press to control the spring load for disassembly.4.1.3
Remove the four (x4) nuts (item 17) connecting the top guide (item 1) to the4.1.4
body (item 4).
TIP:Use a 9/16” socket wrench to remove the nut (item 17).
Figure 4-3 Remove Cap Screws
Ease assembly press up to safely release the spring pressure from the assembly.4.1.5
CAUTION: Spring-loaded Assembly. During valve-spring disassembly, the valve contains springs
under load. DO NOT attempt to disassemble the valve without first reading these instructions or injury
may result. Spring pressure must be adjusted to the minimum and a bench clamp or press used for
disassembly.
CAUTION
23
1
17
4

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Remove cap (item 14) and top guide (item 1) assembly exposing the valve4.1.6
spring internal components for disassembly.
Figure 4-4 Remove Cap and Top
Guide
Remove follower (item 6), outer spring (item 5), inner spring (item 13) and4.1.7
guide (item 7).
Figure 4-5 Remove Follower, Spring
and Guide
Remove stem (item 2).4.1.8
Figure 4-6 Remove Stem
Remove seal retainer (item 12) and shaft seal assembly (item 10) and4.1.9
remove seal from the retainer.
Figure 4-7 Remove Retainer and
Shaft Seal Assembly
1
14
7
6
2
12
10
5
6

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Remove retainer (item 19) with O-ring (item4.1.10
20). Remove O-ring (item 20).
NOTICE: To ensure best practices and
consistency of the qualification process
O-rings should always be replaced.
TIP:Use a non-scratching tool to
remove O-ring (item 20).
Figure 4-8 Remove Retainer and O-Ring
Remove plug (item 3) with O-ring (item 21).4.1.11
Remove O-ring (item 21).
NOTICE: To ensure best practices and
consistency of the qualification process
O-rings should always be replaced.
TIP:Use a non-scratching tool to
remove O-ring (item 21).
Figure 4-9 Remove Plug and O-Ring
Disassemble the cap (item 14) and top guide (item 1) assembly by cutting the4.1.12
seal wire (item 18) and remove the seal screw (item15).
TIP:Use a 7/16” socket wrench to remove the seal screw (item 15).
Figure 4-10 Remove Seal Wire and
Seal Screw
Remove the cap (item 14) from the top guide (item 1).4.1.13
Figure 4-11 Remove Cap
NOTICE
NOTICE
19
20
3
21
15
18
1
14
14
1
19
20
21
3

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Remove the top gasket (item 9).4.1.14
NOTICE: To ensure best practices and consistency of the qualification
process gaskets should always be replaced.
TIP:Use a non-scratching tool to remove gasket (item 9).
Figure 4-12 Remove Top Gasket
Secure the top guide (item 1) in a vise and loosen the top locknut (item 8).4.1.15
TIP:Use a 1-1/2” wrench to remove the top locknut (item 8).
Figure 4-13 Remove Top Locknut
Remove the adjusting screw (item 11) with loosened top locknut (item 8) from4.1.16
the top guide (item 1). Separate the top locknut from the adjusting screw.
TIP:Use a 3/4” wrench and a 1-1/2” wrench to remove the adjusting
screw (item 11).
Figure 4-14 Remove Adjusting
Screw and Top Locknut
Remove flue O-ring (item 22) from body (item 4).4.1.17
TIP:Use a non-scratching tool to remove the O-ring.
Figure 4-15 Remove O-Ring
NOTICE
9
1
1
8
11
8
4
22

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Component Inspection4.2
Key components must be thoroughly inspected during the qualification process. These components include the
components highlighted in Figure 4-18.
Figure 4-16 Component Inspection
NOTICE: Evaluation of critical component metal surfaces using enhanced inspection methods provides a
higher probability of detection of defects than a standard visual inspection and, where applied
appropriately, is recommended by Midland Manufacturing. Facilities performing these inspection methods
must take steps necessary to ensure that their processes, training and personnel certifications are in
compliance with accepted Non-Destructive Testing standards and practices.
The best inspection methods can miss defects when applied incorrectly. A program developed under the
guidance of a qualified American Society of Non-Destructive Testing (ASNT) Level III Technician is
recommended to achieve desired results. Within such a program, specific evaluation criteria for cracks,
pitting, etc., that would identify a part as defective will need to be determined. As a rule, cracks and
pitting detected by these methods or by standard visual inspection are cause for rejection and
replacement of a part.
Refer to AAR MSRP C-111 [M-1002] Appendix J for requirements of non-destructive testing programs
and the responsibilities for their administration.
O-Rings, gaskets and wire seals must always be replaced during this step.
NOTICE
Adjusting Screw (item 11)
Outer Spring (item 5)
Follower (item 6)
Top Guide (item 1)
Retainer (item 19)
Seal Retainer (item 12)
Body (item 4)
Spring Guide (item 7)
Inner Spring (item 13)
Flue (item 23)
Top Locknut (item 8)
Cap (item 14)

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NOTICE: Midland suggests that nuts, washers and studs be regularly replaced during the qualification
process.
NOTICE: Procedures may not cover all conditions encountered in the field. Therefore, it is the
responsibility of the repair agency to obtain approval from Midland for inspection, evaluation, repair and
maintenance procedures not covered herein.
Evaluation of critical component metal surfaces of the valves after cleaning, inspection and specialized
testing performed by agencies other than the repair facility are the responsibility of the repair facility.
Where numerical tolerances cannot be provided, the disposition of the internal integrity and surface quality
of parts is under the jurisdiction of the repair facility and dependent on its experience and judgment.
NOTICE: Without consent from the valve manufacturer or car owner, repair work is limited to
cleaning and polishing. See AAR M1002, Paragraph A3.11.1 of the Tank-Car Specifications.
Adjusting Screw Threads Inspection4.2.1
Visually inspect the adjusting screw (item 11). It should be free of corrosion,
nicks, dents, scratches and pits. If any flaws are detected, replace this part.
Figure 4-17 Adjusting Screw
Inspection
Follower Inspection4.2.2
Visually inspect the follower (item 6). It should be free of corrosion, nicks,
dents, scratches and pits.
Clean and inspect the surface by sanding with emery paper (400-grit). If this
does not effectively clean the surface, replace this part.
Figure 4-18 Follower Inspection
NOTICE
NOTICE
NOTICE
6
11

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Valve Stem Inspection4.2.3
Remove scale, residual product and other foreign
material from the stem (item 2).
Also, inspect for corrosion pitting. Any corrosion pitting
is reason for rejection since it may indicate more severe
corrosion and the starting point for difficult-to-detect
cracking.
NOTE:Use of Enhanced Inspection Methods,
(LPI, MPI, etc.) is recommended.
CAUTION: Check for Cracks. Cracks are
stress concentrators and can cause catastrophic
failure of the stem and uncontrolled venting.
Figure 4-19 Valve Stem
WARNING: Valve-Stem Failure. Cracks and corrosion of pressure relief valve stems can result in
stem failure and uncontrolled venting.
WARNING: Machining Not Allowed. Without consent from the valve manufacturer or car owner,
machining, grinding, welding or other alterations to the valve seat or stem seat is not allowed per AAR
M1002, Paragraph A3.11.1 of the Tank-Car Specifications.
Stem Concentricity4.2.4
The valve stem must be straight within 0.025” (maximum). If the measurements are greater than 0.025”,
replace the stem.
NOTICE:Valve-stem concentricity can be checked using a uni-level concentricity fixture and gauge (not
supplied by Midland). For this or any other devices used to measure concentricity, refer to your
company’s or to your specific instrument’s IOM for proper use instructions.
WARNING: Valve-Stem Eccentricity. Excessive valve-stem eccentricity will cause binding that can
result in high start-to-discharge pressure settings, reduced valve capacity and/or low vapor-tight
pressures.
WARNING: Valve-Stem Straightening. Straightening of the stem by bending it in a press may result in
the buildup of uneven stresses in the stem, which may result in valve malfunction.
NOTICE
CAUTION
WARNING
WARNING
NOTICE
WARNING
Inspect and
Clean Stem
2

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Spring Inspection4.2.5
The springs (items 5 and 13) are highly stressed parts. The exterior surfaces
must be free of pitting, cracks and corrosion. If necessary, use magnetic-
particle or dye-penetration inspection (performed by certified and trained
personnel) to evaluate the exterior surface and ensure that it is free of cracks
and corrosion pits. If any excessive wear over 0.030” of the area is measured
or observed, the spring cannot be repaired and must be replaced.
NOTE:Use of Enhanced Inspection Methods,
(LPI, MPI, etc.) is recommended.
Figure 4-20 Spring Inspection
WARNING: Valve-Spring Failure. Defects in coil springs, such as cracks and corrosion pits, can act as
stress concentrators. Failure to detect these defects can result in coil-spring breakage and uncontrolled
valve venting.
Test the springs by pressing them to 80% of maximum deflection in a press for two (2) minutes. Remove from
the press and then measure the spring free-height. If free-height is less than the minimum indicated in Table 4-
2, replace the spring.
WARNING: Deficient Valve Travel. Coil springs that have taken a “set,” resulting in an undersized free-
height, will not allow the valve to open fully. The spring should not be bowed more than 1/4" when in the
assembled position. Bowing in excess of this amount can cause the spring to rub against the inside wall
of the nozzle or guide tube and adversely affect the pressure settings. If any of the defects mentioned
above are observed, the spring cannot be repaired and must be replaced.
Spring Part Number
Wire Size (REF) (Inches)
Height at 80% of Max.
Deflection (Inches)
Minimum Free-Height
(Inches)
15-150-MO
0.28
2.80
4.00
15-225-SS
0.28
3.13
4.80
15-300-SS
0.31
3.30
4.88
15-375-SS
0.34
3.61
5.00
15-450-SS
0.38
3.74
5.06
Table 4-2 Minimum Free-Heights for Spring After Pressing 80% of the Maximum Deflection for Two (2) Minutes
NOTICE
WARNING
WARNING
5

A-14150/A-14499, Rev. 1
Page 18 of 31
Manual content is subject to change.
Visit midlandmfg.com for latest manual revision and revision history.
Plug Inspection4.2.6
Visually inspect the plug (item 3) paying close
attention to sealing surfaces. It should be free
of corrosion, nicks, dents, scratches and pits.
Since the O-rings must seal against these
surfaces, any irregularities can cause the
valve to leak. Clean these areas by sanding
lightly with emery paper (400-grit). If this does
the effectively clean the part, replace this part.
The plug must be free of gouge marks,
corrosion, pits and rust. If present, this part is
rejectable and should be replaced.
The sealing surface is the crown of the seat.
Clean the seat with emery paper (400-grit)
then wipe it clean with a cloth and a suitable
solvent. Run your fingernail aroudn the surface
to detect any flaws. If any flaws are found, the
part is rejectable and should be replaced.
Figure 4-21 Plug Inspection
Retainer Inspection4.2.7
Visually inspect the retainer (item 19) paying close attention to sealing
surfaces. It should be free of corrosion, nicks, dents, scratches and pits.
Since the O-rings must seal against these surfaces, any irregularities can
cause the valve to leak. Clean these areas by sanding lightly with emery
paper (400-grit). If this does the effectively clean the part, replace this part.
The retainer must be free of gouge marks, corrosion, pits and rust. If present,
this part is rejectable and should be replaced.
Figure 4-22 Retainer Inspection
Body Inspection4.2.8
Visually inspect the valve body (item 4) paying close attention to sealing
surfaces and seat. It should be free of nicks, dents, scratches and pits.
Since the O-rings must seal against these surfaces, any irregularities can
cause the valve to leak. Clean these areas by sanding lightly with emery
paper (400-grit). If this does not effectively clean the part, replace the part.
The body must be free of gouge marks, corrosion, pits and rust. If present,
this part is rejectable and should be replaced.
Figure 4-23 Body Inspection
3
Inspect O-Ring
Grooves
19
4
3
Seat Sealing Surface
O-Ring Sealing Surface
Valve Mounting Surface

A-14150/A-14499, Rev. 1
Page 19 of 31
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Guide Inspection4.2.9
Visually inspect the guide (item 7).
Clean and inspect the surface by sanding with emery paper (400-grit). If this
does not effectively clean the surface, replace this part.
Figure 4-24 Guide Inspection
Seal Retainer4.2.10
Visually inspect the seal retainer (item 12).
Clean and inspect the surface by sanding with emery paper (400-grit). If this
does not effectively clean the surface, replace this part.
Figure 4-25 Seal Retainer
Inspection
Threaded Components4.2.11
All threaded components must be thoroughly inspected and cleaned, or replaced. Inspect threads for any sign
of excessive wear, corrosion, pitting or other defects. If any are found, the part is rejected and should be
replaced.
7
12

A-14150/A-14499, Rev. 1
Page 20 of 31
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O-Ring and Gaskets Inspection4.2.12
O-rings ( items 20, 21, 22 )and gasket (item 9) must be replaced at the time of
the periodic valve retest and when the valve is disassembled.
CAUTION: O-ring Degradation. O-rings develop micro-cracks, can
swell or shrink, and become harder or softer with age and chemical
exposure. An O-ring that fits loosely in the cap, or can only be pushed
into the O-ring retainer with difficulty, is quite likely not the correct size.
Many of Midland’s O-rings are made on special molds to non-standard
sizes and are obtainable only from Midland.
CAUTION: Defective Parts. If any parts appear defective, it is
recommended they be replaced, or consult with Midland for
recommended repair techniques when applicable.
Figure 4-26 Elastomer Inspection
Special Inspection Considerations4.2.13
Previous procedures may not cover all conditions encountered in the field. Therefore, it is the responsibility of
the repair agency to obtain approval from Midland for inspection, evaluation, repair and maintenance
procedures not covered herein.
Facilities performing recommended dye-penetration and magnetic-particle testing must carry out such testing
accoording to a qualified procedure conducted by certified trained personnel.
Evaluation of critical-component metal surfaces of the valves after cleaning, inspection and specialized testing
performed by agencies other than the repair facility are the responsibility of the repair facility.
Where numerial tolerances cannot be provided, the dispostion of the integral integrity and surface quality of
parts is undet the jurisdiction of the repair facility and dependent on its experience and judgment.
CAUTION
20
21
22
9