WRC Approved Rubber Sheets

Potable Water

Water intended for human consumption without imparting any toxic effect is drinking water. Water of sufficient quality to serve as drinking water is termed as potable water whether it is used as such or not. The non-metallic materials can cause changes in water quality when it comes in contact with it. These changes can affect the water quality in respect to:-

  • Odour & Flavour

  • Taste

  • Appearance of Water

  • Growth of aquatic microorganisms

  • Cytotoxity, i.e., extraction of substances to water that could cause adverse effect on public health

  • Mutagenicity

  • Extraction of metals

BS 6920 and its modified version AS/NZS 4020:2002 (for Australian and New Zealand requirements) is the method for testing the water quality –i.e, ‘Testing of products for use in contact with drinking water’ and any non-metallic product should comply with these test requirements for getting the approval given by Water Quality Centre (WQC).

EPDM Rubber
(Ethylene-Propylene-Diene-Monomer)

EPDM rubber is an elastomer which is characterized by wide range of applications. It is also a high performance rubber which has the Water Research Council approval recommended for sealing against potable water. Some most important and versatile properties of EPDM rubber are

  • Excellent resistance to oxidation, heat, weathering, ozone and polar fluids – known as ‘Crackless Rubber’.

  • High performance rubber with lowest specific gravity which can produce very light weight materials.

  • Resistant to hot water, steam and chemicals.

  • Wider service temperature range, from - 55ºC to +150ºC.

Zenith PWS has been developed for using in contact with drinking water which has been met all the technical and biological property requirements as tested by following the corresponding Standards. The test requirements and results are mentioned herewith in Annexure A and Annexure B.

Application Scope

Zenith PWS is a high performance and low specific gravity (1.13) EPDM rubber compound which can be applied for water fitting (supplying) parts e.g., lining, joining, gaskets, membranes, cisterns, O-rings, washers that are used in contact with drinking water.

  
 

Annexure A
Technical Specifications & Test results for WQC approved Zenith Potable Water Sheet (PWS)
Polymer Type : 100% EPDM
 
Properties Specification Test Method Observations
Color Black Visual Black
Finish Smooth/Cloth N.A. N.A.
Operating Temperature
Min Temperature
Max Temperature
Intermittent
-40ºC
100 ºC
120 ºC
ASTM D 746
BS 903, Part A25
-40 ºC
120 ºC
 
Physical Properties
Hardness, IRHD 68 - 73 ASTM D 1415
BS 903,Part A26		 71º
Density, gm/cc 1.13 ASTM D 297
BS 903, Part A1		 1.12
Tensile Strength, MPa, min 11-12.5 MPa BS 903,Part A2
ASTM D 412		 13
Elongation at Break, % 328 – 420% BS 903,Part A2
ASTM D 412		 340
Change In Physical Properties After Ageing @ 70º/48 hrs
Change in Hardness
(IRHD Points), max		 66 – 75 +2 º BS 903, Part A19
BS 903,Part A26
ASTMD573
ASTMD1415 		+2
Change in Tensile Strength, MPa - 8.5 BS 903,Part A19
BS 903,Part A2
ASTMD 573
ASTM D 412 		- 4.92
Change in Elongation at Break, % - 16.5  BS 903, Part A19
BS 903,Part A2
ASTM D 573
ASTM D 412		 - 12.1
Compression Set,
% @22hrs/70ºC		 6.9 – 8.7 % BS 903, Part A6
ASTM D 395 		7.6
 

Annexure B
Biological Requirements & Test Report for WQC approved Zenith Potable Water Sheet (PWS)
Test Results of Water Extract as per AS/NZS 4020:2005
 
Appendix Test Results
C Taste of Water Extract Passed when tested at an exposure of 3000mm2 per liter
D Appearance of Water Extract Passed when tested at an exposure of 15000mm2 per liter
E Growth of Aquatic Micro-organisms Passed at an exposure of 6154 mm2 per liter
F Cytotoxic Activity of Water Extract Passed at an exposure of 3000mm2 per liter
G Mutagenic Activity of Water Extract Mutagenic Activity of Water Extractq
H Extraction of Metals Passed when tested at an exposure of 1500mm2 per liter
 

Salient Features

  1. Complies with all the requirements: Materials or substances , either alone or in combination , which cause or likely to cause any contamination of water should not use in the construction, installation, renewal, repair or replacement of any water fitting which conveys water for domestic and cooking purposes. WQC approved Zenith PWS rubber compound is solely concerned with public health which has given satisfactory results against microbial growth and cytotoxicity when tested according to AS/NZS 4020:2005 . It is also complying with BS 6920 requirements.
     

  2. Excellent outdoor stability & durability: Ethylene-Propylene ter-polymers have fully saturated hydrocarbon backbones, giving excellent resistance to ozone and oxygen. Zenith PWS is a high kind of water and weather proof material with best performance.
     

  3. Resistant to mild acids and alkalis at wide range of temperature:  Because of the highly saturated non-polar structure of EPDM rubber, it has better resistance to chemicals and environment than any other polymer. Its inert nature against corrosion permits it to use in chemical plants also for their supplying parts.
     

  4. Suitability for supplying cold and hot water: Because of its serviceability over a wide range of temperature (-40ºC to + 120ºC ) the rubber sealing will not embrittle or freeze at the ice point of water, nor it will be softened in the contact of domestic hot water. The test reports of  Water Quality Centre, Australia, shows that there is no generation of toxicity or change in quality of water in the specified temperature range.
     

  5. No maintenance is required for the WQC approved Zenith PWS rubber compound: As the EPDM rubber compound does not deteriorate due to weather, heat, sunlight and oxidation virtually no maintenance is required for the sealing.
     

  6. Better sealing (joining) property than the other water fitting materials:  WQC approved Zenith PWS rubber compound has better sealing and leak-proofing property as compared to the conventional materials like metals and plastics. Being an elastomer, it is also free from the chances of galvanic corrosion and leaching of metals which is severe for metal-sealing as well as improved adhesion property and cold crack resistance than plastics like PTFE etc.