EPDM Cone for Gauge Glass

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Forming the main seal between the tubular gauge glass and the Water Gauge Mount, these conical shaped gauge glass cones are available to suit various glass thicknesses. Featuring a high temperature EPDM construction, these cones will suit an AB12 Klinger, Hawleys BGM, Mala as well as any other Water Gauge Mount that shares the same cone dimensions. These are usually changed out on every quarterly boiler service. This EPDM compound took three years of research and trials to settle upon the best blend with great results even on boilers where other rubbers perish quickly.

Product Bore Size To Suit Glass O.D
EPDMCone-1 3/4" 18mm to 19mm
EPDMCone-2 1/2" 12mm to 12.5mm
EPDMCone-3 5/8" 15mm to 16mm

Test Results

Item Measurement Result Test Standard
Hardness degree 75 GB/T 531.1-2008
Density g/cm³ 1.171 GB/T 533-2008
Tensile Strength Mpa 20 GB/T 528-2009
Elongation at Break % 265 GB/T 528-2009
Set after Break % 12 GB/T 528-2009
Compression set (125°C*24H) % 16 GB/T 7759-1996
Temperature °C -20~200°C GB/T 3512-2014

Gauge   Mount Suit Glass ØA ØB ØC D E
3/4" 3/4" 33.5 21 28.5 5.5 23
3/4" 5/8" 33.15 15 28.7 5.85 23.25
3/4" 1/2" 33.15 11.95 28.7 5.85 23.25
1/2" 1/2" 28.8 12.2 23.5 3.25 17.5

All dimensions in mm unless otherwise stated

Bore 3/4", 1/2" & 5/8" 
Suits Glass O.D 3/4" (19mm), 1/2" (12mm) & 5/8" (16mm)
Suits Water Level Gauge Hawleys, Klinger, Mala etc

  • What is an EPDM Cone?

    An EPDM cone or rubber cone is used to form the seal between the boiler gauge mount and the sight glass that connects the top and bottom mount. These are sometimes made of other compounds (of which we have tried many) however EPDM is the most common as it can tolerate the PH of the boiler and the temperatures involved.

  • How does a Rubber Cone Work on a Boiler Gauge Mount?

    The rubber cone seals between the gauge mount body, the glass tube and the tightening nut of the gauge mount. This allows the water and steam levels that are inside the boiler to be seen on the outside by looking at the sight glass. As the rubber is a softer compound it is ideally suited to form this seal.

  • How long will my EPDM Cone last?

    These are usually replaced every quarter or each boiler service. How long it lasts really depends upon the water quality and PH of the boiler. We have tried many different compounds during R&D including FKM but always come back to high temperature EPDM as the best all rounder. It is not perfect and will perish faster on some boilers than others but it is the best allrounder that we have found.

  • How do I install a sealing cone on a Boiler Gauge Mount Sight Glass?

    Boiler technicians have their own ways of installing the rubber cones but we have found the best is to measure and cut the glass then lubricate the glass and the inside of the cone (water is ok). The cone can then be slipped onto the glass and then the glass put into the gauge mount. This can be forced in by hand and then the tightening nut will pull the rubber in the rest of the way.

  • What are typical uses of a Rubber Cone for Boiler Sight Glasses?

    These EPDM cones are designed specifically to fit into the main types of gauge mounts that are used on Boilers. These include Klinger AB12, Hawleys BGM, Mala as well as other brands.

  • Why are our Rubber Cones better than others?

    This is due to the number of different compounds and shapes we tested before we found the best one. This took over three years of testing. The result is a gauge cone which lasts longer, fits tighter and gives you the best result.

  • How long will my product take to get to me? 

    This depends upon where you are based and the freight method chosen. If the express freight option is selected it is usually next day delivery to metropolitan areas in Australia for under 5kg. If free freight has been selected it will go by road freight which can be anywhere from 1 to 10 days depending upon your location. It usually averages 3 days.

  • What warranty do I get?

    All of our products come standard with a 12 month warranty however as this is a perishable item that is replaced every quarter it can't be covered in the same way. How quickly it perishes will depend upon the PH and water quality of the boiler it is used on.