Product Overview

Spirax Sarco BRV71 and BRV73 Series ductile iron direct acting pressure reducing valves are specifically designed for steam systems. BRV71 features threaded connection while BRV73 features flanged connection, allowing flexible selection based on pipeline installation requirements.

The product distinguishes three different downstream pressure ranges through the color of the identification plate (13), meeting pressure control requirements under various operating conditions. When pressure ranges overlap, using the lower range spring is recommended for better control performance. Product usage scope and conditions may be subject to local strict regulations and should be confirmed based on actual application scenarios.

Technical Specifications

Pressure and Temperature Limits

Parameter	Value
Body Design Conditions	PN16
Max Allowable Pressure (PMA)	16 bar g @ 120 °C
Max Allowable Temperature (TMA)	184 °C @ 10 bar g
Min Allowable Temperature	-10 °C
Max Operating Pressure on Saturated Steam (PMO)	10 bar g
Max Operating Temperature (TMO)	184 °C @ 10 bar g
Min Operating Temperature	0 °C (consult Spirax Sarco below this temperature)
Max Downstream Set Pressure	9 bar g
Max Differential Pressure (PMX)	10 bar
Recommended Max Turndown Ratio (at max flow)	10 : 1
Design Max Cold Hydraulic Test Pressure	24 bar g
Max Test Pressure After Assembly	16 bar g

Downstream Pressure Ranges (By Identification Plate Color)

Plate Color	Downstream Control Pressure Range
Grey	0.14 - 1.7 bar g
Green	1.40 - 4.0 bar g
Orange	3.50 - 9.0 bar g

Sizes and Pipe Connections

Connection Type	Size Range	Applicable Standards
Threaded (BRV71)	1", 1¼", 1½", 2"	BSP, NPT
Flanged (BRV73)	DN25, DN32, DN40, DN50	PN16, JIS10, ANSI 150

Kv Values (Valve Fully Open)

Size	Kv Value
1" - DN25	9.3
1¼" - DN32	11.1
1½" - DN40	15.7
2" - DN50	16.2

Conversion Formula

• Cvv (UK) = Kv × 0.963
• Cv (US) = Kv × 1.156

Material Specifications

No.	Component	Material	Standard/Note
1	Body	Ductile Iron	DIN 1693 GGG 40.3 ELNP Coated
2	Pressure Adjusting Spring	Silicon Chrome Alloy	BS 2803 685 A55
3	Adjusting Screw	Carbon Steel	BS 970 230 M07
4	Flat Washer	Stainless Steel	Gr.18/10/3-4A
5	Adjusting Handle	Nylon	10B 140
6	Pin	Stainless Steel	AISI 420
7	Spring Plate	Cast Iron	DIN 1691 GG 20
8	Spring Chamber	Aluminum	2ELNP coated
9	Upper Gasket	Semi-rigid Laminated Graphite	-
10	Lower Gasket	Semi-rigid Laminated Graphite	-
11	Bellows Assembly	Stainless Steel	316L
12	Bellows/Pushrod Assembly	Stainless Steel 15% Graphite Filled	316L
13	Identification Plate	Polypropylene	-
15	Locking Pin	Brass	-
16	Plug (including seal 27)	Stainless Steel	BS 970 431 S29
17	Strainer	Stainless Steel	316L
18	Lower Pushrod	Stainless Steel	BS 970 431 S29
19	Bottom Cover	Ductile Iron	DIN 1693 GGG 40.3 ELNP Coated
20	Bolt	Zinc Plated Steel	BS 3692 Gr. 8.8
21	Bolt	Zinc Plated Steel	BS 3692 Gr. 8.8
22	Washer	Stainless Steel	BS 1449 304 515
23	Guide Bush	PTFE 15% Graphite Filled	-
24	Return Spring	Stainless Steel	BS 2056 316 S42
25	PTFE Gasket	Pure PTFE	BS 6564 Type 2 Gr. B
26	'O' Ring Seal	EPDM	E 0962-90
27	Plug 'O' Ring Seal	EPDM	E 0962-90

Note

Parts 16 and 27 are not shown in the product diagram

Dimensions and Weight (Approximate)

Common Dimensions (Unit: mm)

Size	A	C	D	E	F	G
DN25 - 1"	134	67	153	90	25	84
DN32 - 1¼"	134	67	153	90	25	84
DN40 - 1½"	134	67	153	90	25	84
DN50 - 2"	134	67	153	90	25	84

Note

E is the removal distance

BRV73 Flanged Connection Dimensions (Unit: mm)

Size	B (ANSI 150)	B (JIS 10)	B (PN16)
DN25	170	170	174
DN32	174	175	179
DN40	183	180	186
DN50	186	180	186

Weight (Unit: kg)

Size	BRV71 Threaded	BRV73 Flanged (PN16)
DN25 - 1"	4.40	5.90
DN32 - 1¼"	4.20	7.65
DN40 - 1½"	4.95	8.55
DN50 - 2"	4.75	9.40

Selection Guide

Applicable Media

Saturated Steam, Compressed Air

Sizing Chart Usage

1. In the sizing chart, curves marked with numbers 2, 3, 4, 5, etc. represent upstream pressure, and the left vertical line represents downstream pressure.
2. Based on the required downstream pressure, move horizontally to the right along the left vertical line until it intersects with the corresponding upstream pressure curve.
3. Move vertically down from the intersection point to determine the valve size that meets the flow requirements.

Sizing Example

Example

If the pressure reducing valve flow requirement is 350 kg/h, and pressure needs to be reduced from 8 bar g to 6 bar g:

1. Move horizontally to the right from 6 bar g downstream pressure on the left, intersecting with the 8 bar g upstream pressure curve.
2. Move vertically down from the intersection point, confirming that DN25 size BRV71/73 meets the requirements, therefore select DN25 pressure reducing valve.

Installation Instructions

Installation Requirements

1. Install the pressure reducing valve on horizontal piping following the flow direction arrow on the valve body.
2. For detailed installation and maintenance procedures, refer to the Installation and Maintenance Instructions (IM-P045-10) provided with the product.
3. Confirm that product operating conditions meet technical specification requirements before installation to avoid over-pressure or over-temperature operation.

Spare Parts List

Spare Part Name	Specification/Description	Part Code
Pressure Adjusting Spring	Grey (0.14-1.7 bar g)	K, Q
Pressure Adjusting Spring	Green (1.40-4.0 bar g)	K, Q
Pressure Adjusting Spring	Orange (3.50-9.0 bar g)	K, Q
Control Bellows	Stainless Steel	J
Bellows Pushrod Assembly	Including seat, 'O' ring, lower pushrod and balance bellows	E, C, H
Bottom Cover	-	B
Strainer	-	G
Gasket Set	-	F
Hex Screw (Spring Chamber)	4 pcs	L
Hex Screw (Bottom Cover)	4 pcs	A
Return Spring	-	D

Note

Available spare parts are shown with solid lines; parts shown with dashed lines are not available as spares

Ordering Information

Product Ordering Example

Spirax Sarco BRV71 Pressure Reducing Valve, 1" Threaded Connection, Stainless Steel Bellows, Orange Spring (3.5-9.0 bar g)

Spare Parts Ordering Requirements

1. Specify spare part name and corresponding part code according to the spare parts list.
2. Indicate the size, model (BRV71/BRV73), and pressure range of the product the spare part is for.
3. Spare parts ordering example: Adjusting spring for 1" BRV71 pressure reducing valve, pressure range 3.5-9.0 bar g (Orange)