Product Overview

The Spirax Sarco DP143 series are pilot operated pressure reducing valves manufactured with cast steel bodies. The range covers four service variants: DP143 for steam, DP143G as a soft seal version for compressed air and inert industrial gases, DP143H for high-temperature operation up to 350 C, and DP143Y with a lower-rate pressure control spring for steriliser and autoclave applications.

This product fully complies with the requirements of the EU Pressure Equipment Directive 2014/68/EU and is available with EN 10204 3.1 certification when specified at the time of order placement.

Available Types

DP143	Suitable for steam applications.
DP143G	Soft seal version for compressed air and inert industrial gases. Not recommended for oxygen service.
DP143H	High temperature version for use up to 350 C.
DP143Y	Low-rate pressure control spring version suitable for steriliser and autoclave applications.

Sizes, Connections, and Kv Values

DN15LC low-capacity version, DN15, DN20, DN25, DN32, DN40, DN50, and DN80 are available.

Standard flanges: EN 1092 PN40, BS 10 Table J, and ANSI 300.
Available on request: ANSI 150 and JIS 20.

The Kv maximum values shown below are full capacities and should be used for safety valve sizing purposes only.

DN15LC	DN15	DN20	DN25	DN32	DN40	DN50	DN80
1.0	2.8	5.5	8.1	12.0	17.0	28.0	64.0

For conversion: Cv (UK) = Kv x 0.963, Cv (US) = Kv x 1.156.
Where the internal balance pipe is used the valve capacity will be reduced.

Pressure and Temperature Limits

The product must not be used in the shaded region. Due to the material strength of the main diaphragm chamber, the product must not be used in that region. Use the high temperature DP143H version in the high-temperature region. A-D-E applies to flanged EN 1092 PN40, ANSI 300, and BS 10 Table J. A-B-C applies to flanged ANSI 150. F-G marks DP143G limited to 120 C at 26 bar g.

Two colour coded pressure adjustment springs are available for the following downstream pressure ranges:

Red	0.2 bar g to 17 bar g
Grey	16.0 bar g to 24 bar g
Yellow	0.2 bar g to 3.0 bar g (DP143Y only)

Condition	Variant / Connection	Value
Maximum design pressure	A-B-C	18.9 bar g at 20 C
Maximum design pressure	A-D-E	Limited to 26 bar g
Maximum design temperature	All	350 C at 24 bar g
Minimum design temperature	All	0 C
Maximum upstream pressure for saturated steam service	A-D-E	26 bar g
Maximum upstream pressure for saturated steam service	A-B-C	14 bar g
Maximum operating temperature	DP143	300 C at 26 bar g
Maximum operating temperature	DP143G	120 C at 26 bar g
Maximum operating temperature	DP143H	350 C at 24 bar g
Minimum operating temperature	All	0 C. For lower operating temperatures consult Spirax Sarco.
Maximum differential pressure	A-D-E	26 bar
Maximum differential pressure	A-B-C	14 bar
Maximum cold hydraulic test pressure	All	60 bar g
Max test pressure with internals fitted	All	40 bar g

Materials and Construction

Construction Drawings

Main Component Materials

Items 1 to 10

No.	Part	Detail	Material / Grade
1	Adjustment screw		Steel, BS 3692 Gr. 8.8
2	Adjustment lock-nut		Steel, BS 3692 Gr. 8
3	Washer		Stainless steel, BS 1449 304 S16
4	Spring housing		Cast steel, DIN 17245 GS C25
5	Top spring plate		Stainless steel, BS 970 220 Mo7
6	Pressure adjustment spring		Stainless steel, BS 2056 302 S25
7	Bottom spring plate		Stainless steel, EN 10088-3 1.4057
8	Spring housing securing set	Securing nuts	Steel, BS 3692 Gr. 8
8	Spring housing securing set	Securing studs	Steel, BS 4439 Gr. 8.8
8	Spring housing securing set	DN15 to DN80	Stainless steel, M10 x 30 mm, BS 1449 316 S31
9	Pilot diaphragm		Stainless steel, BS 1449 316 S31
10	Pilot valve housing	DN15 to DN50	DIN 17245 GS C25
10	Pilot valve housing	DN80	GP 240 GH+N

Items 11 to 20

No.	Part	Detail	Material / Grade
11	Pilot valve plunger		Stainless steel, BS 970 431 S29
12	Spring housing cover		Stainless steel, BS 1449 304 S12
13	Pilot valve and seat unit	Standard	Stainless steel, BS 970 431 S29
13	Pilot valve and seat unit	DP143G	Stainless steel / nitrile
14	Internal strainer		Stainless steel, BS 1449 304 S16
15	Body gasket		Stainless steel reinforced exfoliated graphite
16	Main valve return spring		Stainless steel, BS 2056 302 S16
17	Main valve	Standard	Stainless steel, BS 970 431 S29
17	Main valve	DP143G	Stainless steel / nitrile
18	Main valve seat	DP143G	Stainless steel / nitrile
19	Balance pipe assembly		Stainless steel, BS 3605 304 S14
20	Main valve body		Cast steel, DIN 17245 GS C25

Items 21 to 46

No.	Part	Detail	Material / Grade
21	Main diaphragm chamber securing set	Securing nuts	Steel, BS 3692 Gr. 8
21	Main diaphragm chamber securing set	Securing studs	Steel, BS 4439 Gr. 8.8
21	Main diaphragm chamber securing set	DN15 and DN20	M10 x 25 mm
21	Main diaphragm chamber securing set	DN25 to DN50	M12 x 30 mm
21	Main diaphragm chamber securing set	DN80	M12 x 40 mm
22	Main diaphragm chamber		Cast steel, DIN 17245 GS C25
23	Main diaphragm securing set	Securing nuts	Steel, BS 3692 Gr. 8
23	Main diaphragm securing set	DN15 and DN20 bolts	Steel, BS 3692 Gr. 8.8, M12 x 50 mm
23	Main diaphragm securing set	DN25 and DN32 bolts	M12 x 60 mm
23	Main diaphragm securing set	DN40 and DN50 bolts	M12 x 65 mm
23	Main diaphragm securing set	DN80 bolts	M12 x 80 mm
24	Main diaphragms		Stainless steel, BS 1449 316 S31
25	Main diaphragm plate		Stainless steel, BS EN 10088-3 1.4307
26	Push rod		Stainless steel, BS 970 431 S29
27	Control pipe assembly		Stainless steel, BS 3605 304 S14
28	Plug	1/8 inch BSP	Steel
29	Pressure pipe union		Steel
30	Lock-nut		Steel, BS 3692 Gr. 8
45	Body studs		Steel, BS 4439 Gr. 8.8
45	Body nuts		Steel, BS 3692 Gr. 8
45	Body studs and nuts set	DN15 to DN80	M12 x 40 mm
46	Upper main diaphragm chamber		Cast steel, 1.0619+N

For DN80-specific parts, refer to the DN80 construction figure above.

Dimensions and Weights

	EN 1092 PN40	ANSI300	ANSI150	BS 10 Table J
Sizes	A	A	A	A	B	D	E	F	Weight kg
DN15 LC	130	130	122	130	175	405	277	128	15
DN15	130	130	122	130	175	405	277	128	15
DN20	150	150	142	150	175	405	277	128	16
DN25	160	160	156	164	216	440	288	152	23
DN32	180	183	176	184	216	440	288	152	25
DN40	200	209	200	209	280	490	305	185	40
DN50	230	236	230	243	280	490	305	185	42
DN80	310	319	310	325	350	580	322	258	103

Capacity Charts

Steam Capacities

The capacities quoted above are based on valves fitted with an external pressure sensing pipe. Reliance on the internal balance pipe means capacities may be reduced. At low downstream pressure this reduction can be up to 30 percent of valve capacity.

How to use the chart for saturated steam: find the point at which the curved upstream pressure line crosses the horizontal downstream pressure line. A perpendicular dropped from this point gives the capacities of all DP sizes under those conditions. Example: for 600 kg/h reducing from 6 bar to 4 bar, DN32 is the smallest size that carries the required load.

For superheated steam, apply a correction factor to the chart value because of the higher specific volume. Use 0.95 for 55 C superheat and 0.9 for 100 C superheat. In the example above, a DN32 valve passes 740 x 0.95 = 703 kg/h at 55 C superheat, which still satisfies a 600 kg/h requirement.

Compressed Air Capacities

Capacities are given in cubic decimetres of free air per second, dm3/s. Example: to pass 100 dm3/s of free air reducing from 12 bar to 8 bar, find the intersection of the 12 bar upstream curve and the 8 bar downstream line. A DN15LC valve passes only about 57 dm3/s and is too small, while a DN15 valve passes approximately 120 dm3/s and is therefore the correct choice.

Safety Information, Installation, and Maintenance

For full details see Installation and Maintenance Instructions IM-P006-07 supplied with the product.

1. Install the valve in a horizontal pipeline with the flow direction following the arrow marked on the body.
2. For stable control and longer service life, install suitable upstream separation and filtration so condensate and debris do not damage the internals.
3. Capacity and sizing data are based on external pressure sensing pipe installation.

How to Order

Example: 1 off Spirax Sarco DN32 DP143 pilot operated pressure reducing valve fitted with a red pressure adjustment spring and having flanged EN 1092 PN40 connections.

Spare Parts

Available Spares

Maintenance kit: A stand-by set of spares for general maintenance purposes and covering all spares marked *
* Main diaphragm	(2 off)	A
* Pilot diaphragm	(2 off)	B
Pilot valve seal assembly		C
* Pilot valve and plunger assembly		D, E
Main valve assembly		F, H
* Main valve return spring		G
Pressure adjustment spring	Red, DP143 / DP143G / DP143H	J, 0.2 to 17 bar
	Grey, DP143 / DP143G / DP143H	K, 16 to 24 bar
Control pipe assembly		M
Balance pipe assembly		N
* Body gasket	(packet of 3)	O
* Set of spring housing securing studs and nuts	(set of 4)	P
* Set of pilot valve housing securing studs and nuts	(set of 4)	Q
Set of diaphragm chamber securing bolts and nuts	(set of 10) DN15 and DN20	R
	(set of 12) DN25 and DN32	R
	(set of 16) DN40 and DN50	R
	(set of 20) DN80	R
Set of main body studs and nuts (DN80)	(set of 6)	T
Pushrod and main diaphragm plate assembly		V, W, X

Always order spares by using the description given in the Available spares column and state the size and type of pressure reducing valve.

Example: 1 - Main valve assembly for a Spirax Sarco DN15 DP143 pressure reducing valve.

Interchangeability of Spares

The following table shows how certain spare parts are interchangeable between sizes. In the line headed Main diaphragm, the diaphragm used in sizes DN15LC, DN15, and DN20 is common and marked by letter a. The letter b indicates DN25 and DN32 share another common diaphragm. Some parts, particularly pilot and main valve assemblies, are specific to particular models such as DP143G, so interchangeability may be limited by model type.

For storage purposes, the spare parts marked with the dagger note in the original literature are not the same material as those for the DP163 and may not be compatible for interchange. Parts marked with the double-asterisk note are not available for the DP143G.

Size	DN15LC	DN15	DN20	DN25	DN32	DN40	DN50	DN80
Main diaphragm	a	a	a	b	b	c	c	d
Pilot diaphragm	a	a	a	a	a	a	a	a
Pilot valve seal assembly	a	a	a	a	a	a	a	a
Pilot valve and plunger assembly	a	a	a	a	a	a	a	a
Main valve assembly	a	b	c	d	e	f	g	h
Main valve return spring	a	a	a	b	b	c	c	d
Pressure adjustment spring	a	a	a	a	a	a	a	a
Control pipe assembly	a	a	b	c	d	e	f	g
Balance pipe assembly	a	a	b	c	d	e	f	g
Body gasket	a	a	a	b	b	c	c	d
Set of spring housing securing studs and nuts	a	a	a	a	a	a	a	a
Set of pilot valve housing securing studs and nuts	a	a	a	b	b	c	c	d
Set of diaphragm chamber securing bolts and nuts	a	a	a	b	b	c	c	d
Set of main body studs and nuts	-	-	-	-	-	-	-	a