Product - DA4S

​​​​​​​​​​​The BTG Steam Desuperheater DA4S is a combination of an injection nozzle and a control valve. It is inserted in a steam line of minimum diameter DN 150 mm/6". The nozzle is inserted in the steam pipe through a flanged pipe stud that is welded to the steam pipe.​​

​Key features

The cooling water from the water pipe enters the area between the front part of the inlet pipe and the injection nozzle. The control plug is guided in the injection nozzle. The injection nozzle and the sealing surfaces of the control plug are lapped together to ensure tight shut-off. When the plug is in the closed position all water admission holes in the injection cage will also be closed. As the plug lifts from the injection nozzle seat, it simultaneously opens up a number of water admission holes in the injection cage. The number of free ports will therefore be directly related to the lift of the plug. The inlet or admission holes in the injection cage are arranged so that a, from the control point of view, good characteristic is obtained. The cooling water, that enters the injection cage through the tangentially positioned admission holes, is induced to a fast rotation around the tip of the plug and is subsequently ejected through the nozzle as a rapid ly evaporating coneshaped mist. The quantity of injected cooling water depends on the number and size of the ports that are opened up by the control plug. The signal from the temperature transmitter located downstream of the desuperheater controls the position of the plug via the actuator.​


  • Injection nozzle with variable geometry

  • High rangeability, 40:1 (water) and high steam cooling efficiency

  • Combined control valve and injection nozzle in one unit

  • Tight shut-off

  • High reliability and resistance against wear - only one moving part ñ the stem and control plug. Hard-faced control plug and injection nozzle with inner parts of high quality alloy steel.

  • Simple installation - in vertical, horizontal or sloping pipes - min size, DN 150 mm/6".​

Installation example*

*The DA4S must be installed at a 45​º ​angle

Product specification

7 different injection nozzle sizes: A, B, C, D,
E, EO and F with following max. Kv/Cv values:
A = 0.22/0.25
B = 0.6/0.69
C = 1.6/1.8,
D = 3.0/3.4
E = 4.7/5.4
EO = 6.4/7.4
F = 9.7/11.2

Control characteristic (Integrated control valve)
Almost equal percentage (logarithmic)

Control range (Water)

Pressure class
ANSI 600ANSI 1500

Max steam temperature
550∫C (1022∫F)

Housing: Low alloy steel CS17CrMo55, ~ equiv. to ASTM A217WC6
Plug: Stainless steel X20Cr13, ~ equiv. to AISI 420, surface hardened
Atomiser: Stainless steel X20Cr13, ~ equiv. to AISI 420, surface hardened
Nozzle head: Steel X90 CrMoV 18, ~equiv. to ASTM 440B. 
Stuffing box packing: Graphite

Other options

The DA4S is a standardized product, with options limited to what is described within this document. If customized adaptations (e.g. but not limited to accessories, painting, materials, etc.) are desired, IMI CCI recommends the DA4. Note that any price quoted for the DA4S assumes strict adherence to the specifications​

​Pneumatic schematic



Type code


Quality control plan

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Product - DA4S