Spirax Sarco 25P pilot-operated pressure reducing valve ½” - 5” is a self-acting, pilot-operated pressure reducing valve. An external pressure-sensing line detects downstream pressure, adjusts the main valve opening, and maintains stable pressure. The valve can close when there is no downstream load. The pressure reducing valve uses a single-seat main valve with a hardened alloy valve plug. The valve body is made of ductile iron or cast steel, and the pilot valve is bolted directly to the main valve.

Available Models

Model	SKU
DN15 25P SG Blue	6090349
DN20 25P SG Blue	6090352
DN25 25P SG Blue	6090355
DN32 25P SG Blue	6090358
DN40 25P SG Blue	6090361
DN50 25P SG Blue	6090364
DN65 25P SG Blue	6095200
DN80 25P SG Blue	6095203
DN100 25P SG Blue	6095206
DN125 25P SG Blue	3267145
DN150 25P CI Blue	60003504
DN15 25P CS Blue	9307015005
DN20 25P CS Blue	9307020005
DN25 25P CS Blue	7307025005
DN40 25P CS Blue	9307040005
DN50 25P CS Blue	9307050005
DN65 25P CS Blue	9307065005
DN80 25P CS Blue	9307080005
DN100 25P CS Blue	9307100005
DN150 25P CS Blue	9307150006

Downstream Pressure Ranges

• Yellow spring: 0.2 bar g - 2.1 bar g

• Blue spring: 1.4 bar g - 7.0 bar g

• Red spring: 5.6 bar g - 14.0 bar g

Sizes and Pipe Connections

• ½” - 2”: BSPT threaded connection (BS21)

• ½” - 4”: PN16 and PN25 flanges (ductile iron), PN40 flanges (cast steel)

• 5”: PN16 and PN25 flanges (ductile iron)

• Contact Spirax Sarco for other connection sizes.

Weight

Size	Weight (cast iron) (kg)
1/2”	10.8 (threaded), 11.4 (flanged)
3/4”	10.2 (threaded), 12.2 (flanged)
1”	13.6 (threaded), 16 (flanged)
1 1/4”	16 (threaded), 18.8 (flanged)
1 1/2”	15.8 (threaded), 20.4 (flanged)
2”	26 (threaded), 31.2 (flanged)
2 1/2”	62.4 (flanged)
3”	74.6 (flanged)
4”	112.2 (flanged)
5”	132 (flanged)

Materials

No.	Component	Material
1	Valve body	Ductile iron QT400 - 18
2	Bonnet	Ductile iron QT400 - 18
3	Bonnet bolts	Steel SAEJ429 Grs
4	Main valve plug	Stainless steel AISI 420
5	Main valve seat (1/2” - 2”)	Stainless steel AISI 420
5	Main valve seat (2 1/2” - 5”)	Stainless steel AISI 304
6	Main valve seat gasket	Copper
7	Valve return spring	Stainless steel AISI 302
8	Strainer screen	Stainless steel AISI 304
9	Valve stem	Stainless steel AISI 304
10	Stem sleeve (1/2” - 2”)	Brass
10	Stem sleeve (2 1/2” - 5”)	Steel
11	Bonnet gasket	Asbestos-free
12	Spring guide	Steel SAEJ995
13	Nut (1/2” - 2”)	Brass
13	Nut (2 1/2” - 5”)	Steel
14	Pressure balancing line	Stainless steel AISI 304
15	Diaphragm upper cover	Ductile iron QT400 - 18
16	Stem bushing	Stainless steel AISI 304
17	Diaphragm lower cover (1/2” - 2”)	Brass
17	Diaphragm lower cover (2 1/2” - 5”)	Cast iron
18	Pusher guide (1/2” - 2”)	Brass
18	Pusher guide (2 1/2” - 5”)	Stainless steel
19	Diaphragm plate	Ductile iron QT400 - 18
20	Diaphragm plate pusher	Stainless steel AISI 304
21	Nut (2 1/2” - 5”)	Steel
22	Main diaphragm (1/2” - 3”)	Phosphor bronze
22	Main diaphragm (4” - 5”)	Stainless steel
23	Sleeve	Stainless steel AISI 304
24	Short tube and orifice	12L14
25	External pipe assembly	Stainless steel ASTM B280
26	Plug	Steel 12L14
27	Connecting bolts	Steel SAE1060
28	Adjustment screw (1/2” - 2”)	Brass
28	Adjustment screw (2 1/2” - 5”)	Stainless steel
43	Pilot valve spring	Copper, asbestos-free
44	Locknut	Steel
45	Washer	Stainless steel AISI 304
46	Diaphragm upper cover	Ductile iron QT400 - 18
47	Spring plate	Stainless steel ASTM B283
48	Diaphragm lower cover	Brass SAE1010
49	Pilot valve spring	Steel SAE1010
50	Diaphragm plate	Ductile iron QT400 - 18
51	Diaphragm	Phosphor bronze AISI 302
60	Pilot valve gasket	Graphite/asbestos AISI 302
61	Pilot valve mounting nut	Steel SAE J 429 Grs
62	Diaphragm chamber nut	Steel/1 - 18x1” SAE J429 Grs

Installation

Install the pressure reducing valve in a horizontal pipeline with a bypass and isolation valves. Install a steam trap and strainer upstream of the valve. Provide a straight pipe length of at least 10 pipe diameters both upstream and downstream of the downstream pressure-sensing line.

Flow Rate

Size	Cv value
1/2”	3.4
3/4”	6.5
1”	10.5
1 1/4”	14
1 1/2”	20
2”	35
2 1/2”	56
3”	74
4”	115
5”	123

Typical Applications

25P provides accurate and reliable steam pressure reduction from high pressure to the equipment’s effective operating range, helping prevent equipment damage.