610-497-2600

MODELS 71S/171/171P/171S LIQUID RELIEF VALVES

MODEL 171

Features

• Suitable for back pressure to 50 psig (3.45 barg) [1]
• Seats lapped for optimum performance.
• Spherical pivot between disc and spring corrects misalignment and compensates for spring side thrust.
• Stainless steel springs.
• Tested and inspected for pressure setting and leakage.
• All SS 316 model 171S suitable for sanitary applications, depending on requirements.

NOTE

1. Back pressure increases set pressure on a one to one basis, and reduces capacity. Back pressure in excess of 10% of set pressure is not recommended.

GENERAL APPLICATION

Suitable for over pressure relief, pressure regulation, by-pass relief and protection of pumps, tanks, lines and hydraulic systems containing acid, caustic, ammonia and other corrosive liquids requiring iron, steel or SS materials.

TECHNICAL DATA

Connections:Threaded NPT
Temperature range: (Model 71S)-20° to 406°F (-29° to 208°C)
Temperature range: (Models 171, 171P, 171S)-20° to 550°F (-29° to 288°C)
Pressure range: (Model 71S)1 to 250 psig (0.07 to 17.2 barg)
Pressure range: (Models 171, 171P, 171S)1 to 400 psig (0.07 to 27.6 barg)

MODELS OVERVIEW

Model 71S: cast iron body with SS seat and disc. Pressure-tight hood.
Model 171: carbon steel with SS seat and disc. Pressure-tight hood.
Model 171P: as model 171 with packed lift lever.
Model 171S: all 316 SS construction including spring. Available with pressure-tight hood or packed lift lever.

PARTS AND MATERIALS – MODELS 71S, 171, 171S

NoPart NameMaterialMaterialMaterial
1NozzleSS A479-316[1]SS A479-316[1]SS A479-316[1]
2Body gasketPTFEPTFEPTFE
2DiscSS A743-CF8MSS A743-CF8MSS A743-CF8M
4Stem endSS A479-316SS A479-316SS A479-316
5StemSS A479-316SS A479-316SS A479-316
6SpringSS A313-316SS A313-316SS A313-316
7BodyCast iron 126Steel A216-WCBSS A351-CF8M
8Spring stepSS A479-316SS A479-316SS A479-316
9Compression screwSS A479-316SS A479-316SS A479-316
10Cap gasketPTFEPTFEPTFE
11Jam nutSS A479-316SS A479-316SS A479-316
12CapSteel A108Steel A108SS A479-316

MODELS 71S, 171, 171S

PARTS AND MATERIALS – MODELS 171P, 171S WITH PACKED LIFT LEVER

NoPart NameMaterialMaterial
1NozzleSS A479-316[1]SS A479-316[1]
2Body gasketPTFEPTFE
3BodySteel A216-WCBSS A351-CF8M
4DiscSS A743-CF8MSS A743-CF8M
5Stem endSS A479-316SS A479-316
6Spring stepSS A479-316SS A479-316
7StemSS A479-316SS A479-316
8SpringSS A313-316SS A313-316
9Compression screwSS A479-316SS A479-316
10O-ringNBRNBR
11CapSS A296-CF8MSS A296-CF8M
12Jam nutSS A479-316SS A479-316
13Lift camSS A296-CF8MSS A296-CF8M
14Cotter pinSteel commercialSteel commercial
15LeverSteel A108 zinc platedSteel A108 zinc plated
16Drive screwSS commercialSS commercial
17Retainer nutSS A479-316SS A479-316
18Lift nutSteel A108 zinc platedSteel A108 zinc plated

MODELS 171P, 171S

NOTE

1. SS A351-CF8M for 1½” and 2” size.

CAPACITIES – NON-CODE LIQUID – 25% ACCUMULATION (GPM)

Set pressureValveinletandoutletsize
(psig)½”¾”1”1¼”1½”2”
112461019
3246111732
5258142242
7269162649
103711203159
204916284384
30511203453102
40613233961118
50715254468132
60716284875145
70817305281156
80819325587167
90920345992177
100921366297187
11010223765102196
12010233968106205
13011244171110213
14011254273115221
15011254476119229
16012264578123236
17012274781126244
18013284883130251
19013294986134258
20013295088137264
21014305290140271
22014315392144277
23014325494147284
24014325596150290
25015335698153296
260153458100156301
270153459102159307
280163560104162313
290163561106165318
300163662107168324
310163763109171329
320173764111173334
330173865113176340
340173866114179345
350173967116181350
360183968118184355
370184069119186360
380184170121189364
390184170122191369
400194271124194374

NOTE

1. Liquid overpressure factors
To determine capacities at other than 25% overpressure/accumulation, multiply capacity shown by:
10% acc. = 0.6
15% acc. = 0.8
20% acc. = 0.9

DIMENSIONS – MODELS 71S, 171, 171P, 171S

Inlet and outlet female, NPTDimensions (in)
(in)ABC
71S, 171, 171S
C
171P, 171S
Weight
(lb)
½[1]27/166⅞8⅜
¾27/166⅞8⅜2⅝
1211/16789/16
35/162⅛
31/827/16
243/1611⅛12

NOTE

1. ½” size has ¾” outlet.

SELECTION GUIDE

Example:071S-C01-MG0250
Model

071S   Cast iron

0171    Cast steel

171S    Cast SS

171P    Cast steel
Connection size

C       ½" inlet x ¾" outlet

D       ¾" inlet x ¾" outlet

E       1" inlet x 1" outlet

F       1¼" inlet x 1¼" outlet

G      1½" inlet x 1½" outlet

H      2" inlet x 2" outlet
Variation

1       Catalog standard

2       Packed lever (Model 171S)
Design revision

Indicates non-interchangeable revision

Dash (-) if original design
Service


M       Non-code liquid
Spring material

G       316 SS
Set pressure

0005     5 psig
0400     400 psig
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