4.8.25

Control valves

Desuperheaters

General description

Spirax Sarco VAD variable area desuperheaters reduce the temperature of superheated steam by spraying atomised water through a

variable area nozzle, producing near-saturated steam for a wide steam turndown ratio (max 50:1). There are two VAD options available

depending on the Kv value and control rangeability required for the application.

VAD a

in conjunction with a PN9000 series actuator

30 mm travel Kv 0.1 to Kv 1.4

VAD b

in conjunction with a PN9400 series actuator

70 mm travel Kv 1.8 to Kv 4.0

Description

The VAD a variable area desuperheater has been designed to

perform between a Kv of 0.1 to Kv 1.4

The main advantages of the Spirax Sarco VAD is its full

modularity, as the components can be adjusted to meet each

individual application needs; on site if needed. The nozzle can

also be replaced to accommodate a change in flow requirement.

The cooling water is atomised through a number of nozzles which

are successively opened by the linear movement of a plug

controlled by the actuator.

As standard, it is designed and coupled with the PN9000 Series

actuator 30 mm travel.

The steam branch line connection is DN80 as standard, but could

be customised at the required dimension.

The water connection is DN25 as standard, but could be

customised.

The standard dimensional lengths of the top and bottom pipe

extensions of the desuperheater, as well as the position of the

water connection are shown on page 5, but please note that

theses can be customised to meet any specific application to

meet your needs.

Description

As standard, the VAD b is designed to and coupled with the

PN9400 Series actuator. The water atomisation is done through

up to 18 nozzles which are successively opened with the linear

move of the plug.

The steam branch line connection is DN80 as standard, but could

be customised at the required dimension.

The water connection is DN25 as standard, but could be

customised or increased for a higher Kv than 4.

The standard dimensional lengths of the top and bottom pipe

extensions of the desuperheater, as well as the position of the

water connection are shown on page 5, but please note that

theses can be customised to meet any specific application to

meet your needs.

Page 2 of 7

TI-P451-01 CH Issue 3

VAD Variable Area Desuperheaters