Pipeline ancillaries

Sight glasses

Dimensions / weights (approximate) in mm and kg

PN25 ASME 150

Size

A

A

B

E

F

Weight

Spare parts

The spare parts available are shown in solid outline. Parts drawn

in broken line are not supplied as spares.

Available spares

DN15

DN20

DN25

DN32

DN40

DN50

130

150

160

180

200

230

126

142

152

175

199

228

55

55

70

70

90

90

A

45

45

63

63

80

80

10

10

15

15

20

20

3.2

4.1

5.0

5.9

9.1

10.9

3, 4

Set of gaskets

4

Set of windows and gaskets

Please note: For the DN25 and DN32 sizes a set of bolts (16 A/F

M10 x 40) is also included due to the increased thickness of the glass.

B

How to order spares

Always order spares by using the description given in the column

headed 'Available spares' and state the size and type of the sight

glass.

Example: 1 off Set of windows and gaskets for a Spirax Sarco

SG253 sight glass.

5

(not an available

spare)

4

3

4

B

F (window)

E

Safety information, installation and maintenance

For full details see the Installation and Maintenance Instructions

(IM-S32-04) supplied with the product.

Warning:

Under certain conditions corrosive elements in condensate can

affect the inside face of the window, particularly where caustic

alkali and hydrofluoric acid are present. It is recommended that

the sight glass is periodically checked for thinning of the window.

If there is evidence of thinning or erosion damage then the window

should be replaced immediately. Always wear eye protection when

viewing the contents of the sight glass.

Reasonable steps should be taken to protect personnel from injury

in the unlikely event that the window breaks.

Installation and maintenance note:

Sight glasses should have stop valves fitted on both the inlet and

outlet. It is inperative that the upstream stop valve is closed first in

order to prevent overpressurisation.

Sight glasses can be fitted in either a horizontal or vertical line on

the outlet side of a steam trap. Where the trap is a blast discharge

type e.g. thermodynamic, the sight glass must be fitted at least

1 m from the trap. This is to ensure that the glass is not subjected

to thermal shock or pressure.

Ensure access is available for maintenance purposes

Disposal

The product is recyclable. No ecological hazard is anticipated with

disposal of this product providing due care is taken.

How to order

Example: 1 off Spirax Sarco DN20 SG253 sight glass having

an SG iron body, removable toughened glass windows and

flanged EN 1092 PN25 connections.

Recommended tightening torques

Item Size

DN15 - DN20

5

DN25 - DN32

DN40 - DN50

4

3

4

5

(not an available

spare).

N m

12

28

38

or

mm

Qty

8

8

17 A / F

M10 x 30

Pre 08-2010:

17 A/F

M10 x 35

8

Post 08-2010:

16 A/F

M10 x 40

19 A / F

M12 x 40

SG253 Sight Glass

TI-P130-01 ST Issue 9

7.9.8