Spirax Sarco - Catalogo Agosto 2017

5.2.5

Steam

saturation

curve

Steam traps

MST21

Stainless Steel

Balanced Pressure Thermostatic Steam Trap

Balanced pressure

Local regulations may restrict the use of this product to below the conditions quoted.

In the interests of development and improvement of the product, we reserve the right to change the specification without notice.

TI-P125-08

ST Issue 9

Description

The MST21 is a maintainable balanced pressure thermostatic

steam trap designed for relatively small condensate loads usually

associated with instrument tracing applications. It is manufactured

in stainless steel and is corrosion resistant and easily maintainable.

Available types

MST21 Standard capacity for tracing loads (standard unit)

MST21H High capacity for special applications

Note: When placing an order always state the capsule fill.

Capsule fill and operation

Standard capsules are marked with the letter 'STD' for operation at

approximately 10°C below steam saturation temperature.

Optionally the capsule can be supplied for sub cooled 'SUB'

operation at approximately 22°C below steam saturation

temperature or a 'NTS' fill capsule for operation at approximately 4°C

below steam saturation temperature.

Standards

This product fully complies with the requirements of the European

Pressure Equipment Directive 97/23/EC.

Certification

This product is available with a manufacturers' Typical Test Report.

Note: All certification / inspection requirements must be stated at the

time of order placement.

Sizes and pipe connections

MST21 1⁄4" " and 1⁄2" screwed BSP, EN ISO 228-1, or NPT.

MST21H 1⁄2", 3⁄4" and 1" screwed BSP, EN ISO 228-1, or NPT.

Pressure/temperature limits (ISO 6552)

��

Pressure bar g

The product must not be used in this region.

The product should not be used in this region as damage

Materials

No. Part

1 Body

2 Cap

3 Capsule

4 Spring

5 Spacer plate

Strainer screen

(0.8 mm perforations)

7 Gasket

Note: Material grades shown in brackets are nearest equivalents.

to internals may occur.

Material

Austenitic

stainless steel (303)

Stainless steel

PN25

25 bar g @ 300°C

400°C @ 23 bar g

0°C

21 bar g @ 235°C

235°C @ 21 bar g

0°C

Designed for a maximum cold hydraulic test pressure of 38 bar g

ASTM A743 CF16Fa

420A UGIMA AISI 420

Body design conditions

PMA Maximum allowable pressure

TMA Maximum allowable temperature

Minimum allowable temperature

PMO Maximum operating pressure

TMO Maximum operating temperature

BS 2056 302 S26

BS 1449 304 S15

ASTM A240 316L

Minimum operating temperature

Stainless steel

BS 1449 304 S15