Direct Acting Pressure Reducing Valves - Filter

Direct acting pressure
reducing valves

2
Pressure control valves for steam, water
and air mains distribution
Spirax Sarco DRV control valves are specifically designed for
the control of pressure within steam, water and air distribution
mains which operate at pressures up to 40 bar g and
temperatures up to 300°C.
A NITRILE rubber soft seated option Type DRV-G is
available for tight shut-off applications which do not
exceed 90°C, a maximum pressure turndown ratio
of 10:1 is recommended for optimum performance.
Flow from under to over seat
for improved control and longer life.
Stainless steel metal / metal and
NITRILE rubber soft seated options.
Double guided stem for extended valve life.
Balancing bellows provides high closing
differential pressure and improved control.
Spanner operated pressure setting plate
which is light in operation and gives
fine adjustment of downstream pressure.
Bellows stem sealing for
low maintenance and long life.
Chrome vanadium springs, colour coded
for setting range and total interchangeability.
Spring plate with needle roller bearing which
adds to ease of adjustment.
Pressure chamber with fabric reinforced
diaphragms for accuracy and sensitivity.
Range of interchangeable actuators
combined with 6 spring ranges
to give maximum product flexibility.

Valve options
Due to the diverse and often remote nature of distribution pipework, this modern range of products has retained
the feature of being self-powered and therefore provides the major benefits of easy installation and a long, low
maintenance life expectancy.
Set pressures for the DRV cover a wide span of 0.1 to 20 bar g and are available for all DN15 to 100 valve sizes,
with the option of SG iron or cast steel body materials.
When the valves are used on steam which has a temperature in excess of 125°C, the pressure sensing line to the
valve actuator passes through a water seal pot. This allows the use of a fabric reinforced EPDM diaphragm within
the actuator, giving the benefit of greater sensitivity and control accuracy throughout the pressure control range.
For applications where there is rapid fluctuation of pressures or loads the larger volume WS4 - 3 is available.
Actuators are available with NITRILE rubber diaphragms for oil applications.
Although designed for operating on saturated steam a small amount of superheat can be tolerated due to the
cooling affect of the pressure signal line.
The standard DRV has
Water Research Council approval
Certificate No. 9603028
for primary use applications.
Model Size Body material Connections*
How it works
On start-up, the valve is open allowing the medium to flow to the downstream system. Compression is applied
to the control spring through the setting plate using a spanner. The power in the spring is transmitted through the
spring plate to the valve push rod which holds the valve plug in the fully open position. As downstream pressure
increases it acts through a pressure sensing line onto the diaphragm attached to the end of the valve push rod.
Downstream pressure will continue to increase until the pressure acting on the diaphragm, overcomes spring
pressure holding the valve plug in the open position, moving it towards the valve seat to modulate flow and
maintain the required downstream pressure.
An important feature in the operation of the valve
is the use of a balancing bellows to eliminate the
effect of differences in upstream and downstream
pressure on the valve plug which can cause noise
and vibration.
Water seal pot type WS4
Pressure ranges
bar g
DRV7
DRV7G
DN15 - 50 SG iron BSP / NPT
✝ 0.1 -
✝✝ 0.2 -
0.6
1.2
300°C
90°C
DRV7
DRV7G
DN15 - 100 SG iron BS 4504 PN16 / 25
0.8 -
2.0 -
2.5
5.0
300°C
90°C
DRV4
DN15 - 100 Cast steel BS 4504 PN40
4.5 - 10.0 300°C
User benefits
● Long life and reliable performance from the
natural features of a self-powered unit.
● Low installation costs through one trade fix.
● Low maintenance costs
from bellows sealing of the valve stem.
● Accurate and stable control
through the balancing bellows.
Operating limits
25 bar g
25 bar g
40 bar g
DRV4G 8.0 - 20.0 90°C
*ANSI and JIS flanges also available DN32 to DN50 range 0.15 - 0.6, DN65 to DN100 range 0.3 - 0.6 DN65 to DN100 range 0.4 - 1.2
● Close setting of the desired pressure through the
inclusion of fine actuator setting adjustment .
● Simple on site pressure range changes due to
totally interchangeable springs and actuators.
● Safety where steam mains are subject to thermal
shock. This is achieved by including in the range,
PN25 SG (ductile) iron valves - DN15-100.
● Flexibility of choice from a downstream pressure
control range which spans 0.1 to 20 bar g.
● Integrity of shut-off with tight soft seat option.
3

4
Typical applications
Control of steam distribution
Cost effective steam distribution depends upon keeping pipe sizes to the minimum. This in turn, means designing
for the highest acceptable distribution pressure between the boiler house and the areas of steam usage, then
dropping pressure at the working area to the levels for the highest heat transfer, efficiency and safety.
Spirax Sarco direct acting pressure reducing valves are designed specifically to match this task. The installation
sketch above shows a steam pressure reducing station serving the entry to a typical food, textile, industrial
process area or hospital building. A safety valve might be required to meet safety requirements of equipment.
Control of water and air distribution
Pressure reduction in water systems aids both the efficient design of the piping network and protects consumers from:-
Excessive noise from high velocity within their buildings.
High pressure discharge at taps and other outlets.
Climbing overnight pressures when the distribution network is lightly loaded.
The ability to control water entry pressures ensures a balanced distribution network and also limits the
maximum supply volume thus reducing water waste.
The installation sketch above shows the simplicity of a typical water or air pressure reducing station. For water
could be used at the point of entry to an office block, residential block of flats or industrial consumer.
A safety valve might be required to meet safety requirements of equipment.
Where the consumption of water or air is small the Spirax Sarco LRV2 or BRV2 pressure reducing valve is
available. Refer to the relevant sales brochure.

The sizing chart shown below can be used to determine
the Kv value of the required pressure reducing valve for
most steam applications by plotting:-
■ Inlet steam pressure.
■ Valve pressure drop.
■ Steam demand.
Where the Kv value is already known, the chart can be
used to determine valve pressure drop for any given
flowrate. The valve and actuator relationship is simply
established by quoting the pressure setting range.
A
Inlet pressure bar (abs)
Steam flow kg / h (÷3 600 = kg/s)
Valve sizing and selection
0.3
0.4
0.5
1
2
3
4
5
10
20
30
40
50
100
1
2
3
4
5
10
20
30
40
50
100
200
300
400
500
1 000
2 000
3 000
4 000
5 000
10 000
20 000
30 000
40 000
50 000
80 000
200 150 100 50 0
Superheat °C
This sizing chart is empirical and should not be used for critical applications
0.005
0.01
➤
0.03
0.02
0.05
0.1
1.25 1
5
12.5 10
20 16
31.5
40
50
63
80
25
0.2 0.3
0.5
0.125 0.1
0.08
0.2 0.16
0.315 0.25
0.5 0.4
0.8 0.63
2 1.6
3.15 2.5
8 6.3
125 100
200 160
315
400
250
Kv selection example:
Steam demand for process = 3 500 kg / h
Steam pressure upstream of valve = 10 bar (11 bar abs)
Superheat = None
Steam pressure required in process = 4 bar g (5 bar abs)
Valve pressure drop = 11 - 5 = 6 bar g
Draw line A - B at 3 500 kg / h flowrate and from 11 bar abs inlet
pressure to the 6 bar pressure drop line which in this case is the
critical pressure drop line (line C - D).
Drop vertical line (D - E) to meet the 3 500 kg / h flow line and read
the required Kv value at the crossing point (F) i.e. Kv = 28.
Actual valve size can be selected from the Kvs table at the
bottom of page 6. For the above example the selected valve is
the DN50 with a Kvs of 40 being the next highest value above the
design Kv.
Saturated /superheated steam sizing chart
C
Critical pressure drop (bar)
Note: Always use the pressure reducing valve maximum lift Kvs for sizing the safety valve and not the design Kv value.
4
1
F
E
D
2
B
5
5

6
The sizing chart shown below can be used to determine
the Kv value of the required pressure reducing valve for
water applications by plotting:-
■ Inlet water pressure.
■ Outlet water pressure.
■ Water demand.
When choosing the water set pressure, take into
account any likelihood of the pressure being set
higher or the inlet pressure dropping, as this will
reduce the pressure drop through the valve and
consequently affect the capacity. In such cases,
always size for the lowest valve pressure drop.
200
100
50
40
30
20
10
5
4
3
2
1
0.5
0.4
0.3
0.2
0.1
0.05
0.04
0.03
0.02
0.01
0.005
0.004
0.003
Valve sizing for water
Water sizing chart
Kv selection example
Water demand for the building = 25 m³/h
Inlet pressure = 4.0 bar g
Set pressure = 1.5 bar g
Pressure drop = 4.0 - 1.5 = 2.5 bar
Draw line A - B across the chart at 25 m³/ h flowrate and
vertical line C - D upwards from the 2.5 bar pressure drop point.
Where the two lines cross at point E, indicates the required
valve Kv i.e. Kv = 17.
Actual valve size can be selected from the Kvs table at the
bottom of this page. For the above example the selected
valve is the DN40 with a Kvs of 24 being the next highest
valve above the design Kv.
500
400
300
200
100
40
30
20
50
B A
E
Flow l/s
1
0.1
0.01
2
3
4
5
0.2
0.3
0.4
0.5
0.02
0.03
0.04
0.05
Kv m³/h
1 000
500
400
300
200
10
1
0.1
100
50
40
30
20
Note: Always use the pressure reducing valve maximum lift Kvs for sizing the safety valve and not the design Kv value.
10
3
2
4
5
1
0.5
0.4
0.3
0.2
0.1
0.05
0.04
0.03
0.02
Kvs values for DRV reducing valves
Valve size D N 15 D N 20 D N 25 D N 32 D N 40 D N 50 D N 65 D N 80 D N 100
Kvs 3.4 6.5 11.4 16.4 24 40 58 92 145
10
20
30
40
50
100
5 4
3
2
1
0.5
0.4
0.3
0.2
Pressure drop kPa
2
3
4
5
0.2
Pressure drop m wg
0.3
0.4
0.5
10
1
D
Pressure drop bar C
0.1
0.05
0.04
0.03
0.02
200
300
400
500
20
30
40
50
2
3
4
5
0.01
1 000
100
10
2 000
3 000
4 000
200
20
300
400
30
40
0.01
Flow m³ /h

Operating range DRV7
Temperature °C
300
Operating range DRV4
Temperature °C
300
DRV7
Technical information
200
Steam saturation curve
100
A A
0
0 10 20 30 40
Materials
Body SG iron DIN 1693 GGG40.3
Bonnet SG iron DIN 1693 GGG40.3
DRV4
Body Cast steel DIN 17245 GS C-25
Bonnet Cast steel DIN 17245 GS C-25
DRV7 and DRV4
Valves
200
Steam saturation curve
100
A A
0
0 5 10 15 20 25
Pressure bar g
The product should not be used in the red shaded area.
A - A DRV7G limited to + 90°C
Pressure bar g
The product should not be used in the red shaded area.
A - A DRV4G limited to + 90°C
Valve plug Stainless steel BS 970 431 S29
Valve plug Stainless steel BS 970 431 S29
soft seated Nitrile
Valve seat Stainless steel BS 970 431 S29
Valve stem Stainless steel AISI 316
Bellows Stainless steel AISI 316 L
Bonnet gasket Reinforced exfoliated graphite
Maximum differential pressures
DRV7 DN15 to 50 25 bar
DRV7 DN65 to 100 20 bar
DRV4 DN15 to 50 25 bar
DRV4 DN65 to 100 20 bar
Technical data
Maximum temperature
Actuators
EPDM diaphragm 125°C
Nitrile diaphragm 110°C
Maximum operating pressure
Pressure Maximum Actuator
range set pressure (bar) pressure rating
1 0.6 PN2.5
2 1.2 PN2.5
3 2.5 PN6
4 5.0 PN16
5 10.0 PN25
6 20.0 PN25
Material
Actuator housing
Type 1-4 Carbon steel DIN 1614 St W24
Type 5 Carbon steel BS EN 10025 S355 J2G3
Diaphragms
EPDM
Nitrile
Fabric reinforced
Fabric reinforced
Spring Steel Chrome vanadium
How to select
Valve selection is derived from the following:
Connection DN15, 20, 25, 32, 40,
type 50, 65, 80 and 100
DN25
Valve type DRV DRV
Body material
4 = Cast steel
7 = SG iron
Option G = Nitrile rubber soft seated G
Stem sealing B = Bellows sealed B
Spring
setting
range
✝ 1 = 0.1 - 0.6 bar
✝✝ 2 = 0.2 - 1.2 bar
3 = 0.8 - 2.5 bar
Yellow spring
4 = 2.0 - 5.0 bar
5 = 4.5 - 10 bar
Blue spring 2
6 = 8.0 - 20 bar Red spring
Option N = Nitrile diaphragm N
Connections
Screwed BSP or NPT
Flanged PN16, 25 or 40
7
PN25
Water seal pot WS4 or WS4-3 (If required)
WS4 BSP
Connections BSP / NPT or butt weld
Example
DN25 DRV7-B2 flanged PN25, with WS4 water seal pot screwed BSP.
Notes
1. For tight shut-off add 'G' forNITRILE rubber soft seat
i.e. DRV7G-B2.
2. For oil applications add suffix 'N' for NITRILE diaphragm
i.e. DRV7-B2N.
✝ DN32 to DN50 Range 0.15 - 0.6, DN65 - DN100 range 0.3 - 0.6
✝✝ DN65 to DN100 range 0.4 - 1.2
7

➤
D
➤
➤
Flanged valves Screwed valves
A1 ➤
A2 ➤
➤
C
Actuator weight kg (excluding valve)
WS4 water seal pot = 1.7 kg (empty)
WS4-3 water seal pot = 5.4 kg (empty)
➤
➤
B
➤
Dimensions approximate in mm
E
➤
➤
➤
Typical specification
Pressure reduction shall be achieved using direct
acting pressure reducing valves with stainless steel
bellow stem seals and fully balanced trims for high
closing differentials. Trim balancing shall be by plug
balancing on sizes DN15 and DN20 and stainless steel
balancing bellow on sizes DN25 to DN100.
All valves shall be controlled by high quality chrome
vanadium springs and fabric reinforced diaphragms.
Valve bodies shall be either PN25 SG iron or PN40
cast steel dependent upon the maximum operating
pressure.
Valve
Connections
BS 4504 PN40
Upstream pressure range
size Flanged Screwed 1 2 3 4 5 6
A1 D A2 E B C B C B C B C B C B C
DN15 130 97 88 38 537 305 511 250 426 208 426 168 411 143 411 143
DN20 150 107 102 38 537 305 511 250 426 208 426 168 411 143 411 143
DN25 160 117 134 51 546 305 520 250 435 208 435 168 420 143 420 143
DN32 180 142 144 51 608 305 582 250 497 208 497 168 482 143 482 143
DN40 200 152 150 62 608 305 582 250 497 208 497 168 482 143 482 143
DN50 230 167 180 71 611 305 585 250 500 208 500 168 485 143 485 143
DN65 290 187 - - 633 305 607 250 522 208 522 168 507 143 507 143
DN80 310 202 - - 639 305 613 250 528 208 528 168 513 143 513 143
DN100 350 237 - - 744 305 718 250 633 208 633 168 618 143 618 143
Valve weight kg (excluding actuator)
Valve size DN15 DN20 DN25 DN32 DN40 DN50 DN65 DN80 DN100
Yellow / Blue spring
DEP4
Red spring
11.0
12.0
12.4
13.4
14.6
15.6
19.8
21.2
21.2
22.6
25.2
26.6
35.5
37.3
41.3
73.1
58.3
60.9
Yellow / Blue spring 10.8 11.8 14.0 18.8 20.4 23.0 31.7 38.2 53.9
DEP7 Red spring 11.8 12.8 15.0 20.2 21.8 24.4 33.5 40.0 56.5
Reduction for
screwed connections
-1.7 -2.2 -2.2 -3.6 -3.9 -5.5 - - -
Type 1 2 3 4 5
Weight 12.3 6.5 3.9 2.5 2.6
Some of the products shown may not be available in certain markets.
Spirax-Sarco Limited, Charlton House,
Cheltenham, Gloucestershire, GL53 8ER UK.
Tel: +44 (0)1242 521361 Fax: +44 (0)1242 573342
E-mail: enq@spiraxuk.attmail.com
Internet: www.spirax-sarco.com
© Copyright 1999 Spirax Sarco is a registered trademark of Spirax-Sarco Limited
SB-S12-01 CH Issue 8
DRV