The Armstrong GD-45 is a compact, high-performance, direct-acting pressure reducing valve designed for steam, air, and non-corrosive gas service. Inexpensive to buy and use, it is ideal for moderate flow applications that do not justify the higher cost of pilot-controlled valves. The GD-45 is well-suited for laundry and dry-cleaning equipment, hospital equipment, tire molds, humidifiers, small heaters, and applications in food processing. It provides tight, quick, and easy installation.

Features and Benefits

Quick, easy installation

• Lightweight and compact design.
• Piping supports the valve of ductile iron for greater durability and higher inlet pressure.
• Screwed connections.
• No external sensing lines or parts needed.
• Maximum turndown ratio of 10:1.
• ANSI Class IV shutoff.

Simple selection

• Available in 1/2", 3/4", and 1" sizes (normally match pipe size).
• Three pressure range springs available. For best control when ranges overlap, use the smaller range spring.

Long life and easy maintenance

• Highly resilient phosphor-bronze bellows.
• Hardened stainless-steel working parts.
• Integral strainer (removable for cleaning) for protection from wear or dirt.
• Teflon gaskets used at all joints for improved leakage prevention.

Specifications and Materials

Service	Inlet Pressure psig (barg)	Reduced Pressure psig (barg)	Minimum Differential psig (barg)	Maximum Temperature °F (°C)	Body Material	Valve/Seat Material	Bellows Material
Steam, Air, Non-Corrosive Gases	15 - 300 (1 - 20)	3 - 15 (0.21 - 1.0) Yellow 7 - 60 (0.5 - 4.0) Blue 50 - 140 (3.4 - 9.6) Green	7 (0.48)	450 (232)	ASTM A536 Ductile Iron	Hardened Stainless Steel AISI 420	Phosphor Bronze ASTM B103

Dimensions and Weights

Symbol	1/2" (15 mm)	3/4" (20 mm)	1" (25 mm)
L	4-3/8" (111 mm)	4-3/8" (111 mm)	4-3/8" (111 mm)
H1	1-7/8" (47 mm)	1-7/8" (47 mm)	1-7/8" (47 mm)
H	8-1/2" (216 mm)	8-1/2" (216 mm)	8-1/2" (216 mm)
Weight	7 lb (3.2 kg)	7 lb (3.2 kg)	7 lb (3.2 kg)
Cv	1.3	1.5	2.5

Capacities

INFO

GD-45 capacities cannot be determined with a formula—consult the capacity tables below. For air capacities in scfm, multiply steam capacities (lb/hr) by 0.36. For air capacities in m³/hr, multiply steam capacities (kg/hr) by 1.35. Maximum pressure reduction ratio is 10:1.

Inlet	Outlet	1/2"	3/4"	1"	Inlet	Outlet	15 mm	20 mm	25 mm
psig	psig	lb/hr	lb/hr	lb/hr	barg	barg	kg/hr	kg/hr	kg/hr
Cv Factor		1.3	1.5	2.5	Cv Factor		1.3	1.5	2.5
15	7	49	56	92	1.0	0.5	22	25	42
20	13	53	61	105	1.4	0.9	24	28	48
20	7	42	55	63	1.4	0.5	19	25	35
30	23	62	71	112	2.0	1.6	28	32	51
30	15	53	60	101	2.0	1.0	24	27	46
30	3	33	40	60	2.0	0.2	15	18	27
40	32	99	121	187	2.8	2.2	45	55	85
40	20	79	97	159	2.8	1.4	36	44	72
40	4	40	55	77	2.8	0.3	18	25	35
50	40	130	143	242	3.4	2.8	59	65	110
50	20	99	115	187	3.4	1.4	45	52	85
50	5	48	62	88	3.4	0.3	22	28	40
60	48	137	154	265	4.0	3.3	62	70	120
60	40	150	165	289	4.0	2.8	68	75	131
60	18	90	104	170	4.0	1.2	41	47	77
60	6	55	73	99	4.0	0.4	25	33	45
80	64	176	205	342	5.5	4.4	80	93	155
80	54	187	225	353	5.5	3.7	85	102	160
80	23	121	137	220	5.5	1.6	55	62	100
80	8	60	77	108	5.5	0.5	27	35	49
100	80	203	242	397	6.9	5.5	92	110	180
100	66	225	262	437	6.9	4.5	102	119	198
100	40	198	231	375	6.9	2.8	90	105	170
100	10	68	79	132	6.9	0.7	31	36	60
120	96	231	276	452	8.3	6.6	105	125	205
120	70	276	311	518	8.3	4.8	125	141	235
120	45	240	267	450	8.3	3.1	109	121	204
120	12	110	121	198	8.3	0.8	50	55	90
150	120	287	333	551	10.3	8.3	130	151	250
150	85	364	421	705	10.3	5.9	165	191	320
150	55	298	353	595	10.3	3.8	135	160	270
150	15	132	165	254	10.3	1.0	60	75	115
180	140	408	485	794	12.4	9.7	185	220	360
180	115	430	507	860	12.4	8.0	195	230	390
180	70	386	430	739	12.4	4.8	175	195	335
180	18	165	187	309	12.4	1.2	75	85	140
200	140	461	518	871	13.8	9.7	209	235	395
200	115	474	540	904	13.8	8.0	215	245	410
200	80	430	496	827	13.8	5.5	195	225	375
200	20	209	242	386	13.8	1.4	95	110	175
225	140	485	573	948	15.5	9.7	220	260	430
225	115	496	584	961	15.5	8.0	225	265	436
225	85	463	540	904	15.5	5.9	210	245	410
225	23	254	298	496	15.5	1.6	115	135	225
250	140	525	606	1014	17.2	9.7	238	275	460
250	120	551	584	1038	17.2	8.3	250	265	471
250	70	463	529	893	17.2	4.8	210	240	405
250	25	276	320	529	17.2	1.7	125	145	240
300	140	528	616	1023	20.0	9.7	240	280	465
300	120	551	627	1038	20.0	8.3	250	285	477
300	70	484	550	913	20.0	4.8	220	250	415
300	30	319	352	583	20.0	2.0	145	160	265

Installation Instructions

Recommended Accessories

1. An Armstrong Inverted Bucket Steam Trap is recommended to drain condensate at the inlet of the Pressure Reducing Valve (PRV). A Liquid Drainer is recommended for air service.
2. An Armstrong Y-Strainer (20-100 mesh, depending on system dirt) should be installed before the PRV to reduce the chance of dirt fouling.
3. Pressure gauges should be installed before and after the PRV.

4. If the system cannot be turned off to service the PRV, piping a by-pass line with a high-quality globe valve around the PRV will allow manual system operation while the PRV is being serviced.
5. Install the PRV with the flow in the direction of the arrow on the body.

WARNING

Do not install quick opening or closing valves downstream of the PRV.

Installation for Air Service

Installation for Steam Service

Start-Up and Adjustment Procedures

Improper adjustment of the pressure reducing valve may cause hunting, scale problems, water hammer, etc., and damage to the valve itself. Damaged pressure gauges, leakage or opening of a bypass valve, or clogging of an inlet strainer may cause problems similar to that of a malfunctioning reducing valve. Adjust the valve as follows:

1. Close the gate valves before and after the pressure reducing valve. Open the globe valve slowly in the bypass line and blow down the inlet piping. Adjust the opening of the bypass valve so the safety valve does not blow. After blowing the system down, close the bypass valve.
2. Slowly open the inlet side gate valve to the fully open position, and partially open the outlet valve so only a small amount of steam or air can pass.
3. To increase the downstream pressure, turn the adjusting screw clockwise until the desired pressure is obtained on the downstream pressure gauge.
4. Slowly open the outlet valve to the fully open position.

Troubleshooting Guide

Problem	Causes	Solutions
The desired pressure cannot be obtained.	The inlet pressure is too low or high.	Change the pressure to the appropriate level.
	The sensing port of the outlet pressure is clogged with foreign matter.	Disassemble and clean the sensing port.
	The valve size is smaller than what is required.	Change the valve size to the appropriate one.
	The adjustment is not appropriate.	Readjust according to the adjustment procedure. (See start-up procedure)
	The inlet strainer is clogged by foreign substance.	Disassemble and clean the strainer.
	The pressure gauge is not functioning properly.	Replace the pressure gauge.
The outlet pressure rises higher than the specified pressure	The valve or valve seat is contaminated by foreign substance.	Disassemble and clean the valve or the seat.
	The by-pass valve is leaking.	Repair or replace the by-pass valve.
Abnormal noise is heard.	The reducing ratio is excessively large.	Reduce pressure by staging with second PRV.
	Water hammer (for steam service).	Install a steam trap at the reducing valve inlet.
	There is a fast closing valve near the PRV.	Provide as long a distance as possible between the two valves.

Maintenance

Disassembly

DANGER

Eliminate pressure from inside the valve. Make sure the valve is completely free from pressure before proceeding.

1. Turn the adjusting screw (11) counterclockwise to make the spring (12) free (not loaded).
2. Remove the bolts (15) and take away the spring housing (2) (the handle cannot be disassembled). Take out the spring (12), bellows (10) and valve rod (8).
3. Unscrew (counterclockwise) the cap (3) and take out the spring (13), screen (9) and valve (7) from the body (1).

Reassembly

1. Check all parts to make sure they are in good condition before putting back together.
2. Lap valve (7) and valve seat (6) with 1000 grit lapping compound if needed to ensure no leakage.
3. Reassemble in reverse order as disassembly.

TIP

Replace all gaskets where disassembly is required.