EN 549-1994 pdf download.Rubber materials for seals and diaphragms for gas appliances and gas equipment.
3 Definitions
For the purposes of this standard the following definitions apply.
3.1 component
Finished product manufactured from rubber material.
3.2 seal
A component used as an Interface between parts of a gas appliance or parts of gas equipment to achieve gas tightness.
3.2.1 static seal
A component which ensures a seal between two parts of a gas appliance or parts of gas equipment which do not have relative movement (‘0’ rings, sheet gaskets, etc.).
3.2.2 dynamIc seal
A component which ensures a seal between two parts of a gas appliance or parts of gas equipment which have relative movement (lip seals, valve pads and some ‘0’ rings).
3.3 dIaphragm
A membrane of rubber material located in a fixture and serving as a flexible gas tight partition between two chambers.
3.4 reInforcement
Woven or unwoven material arranged in or on the rubber type material, thus reinforcing certain properties of such, for example the bursting strength of diaphragms.
4 Manufacturer’s declared information The manufacturer responsible for the production of material complying with this standard shall ensure that he declares the following information which shall be documented:
— a unique material reference;
— the nominal hardness;
– the maximum working temperature of the
material;
— the minimum working temperature of the
material;
— whether the material is resistant to ozone;
— for reinforced material, a full specification of
the reinforcement, for example type of material,
basic construction and decitex.
N&rE. It is recommended that diaphragms should be ozone resistant. Because of the potential interruption of any protective surface coating, such as waxes, by dynamic flexing such methods of protection against ozone attack shall not be used without additional protective additives.
EXAMPLE: The classification of a rubber material applicable over the temperature range of —20 °C to +80 °C with a declared nominal hardness of 70 IRHD would be B2/H3.
6 Requirements
6.1 General
Materials shall be free from porosity, Inclusion, blisters and surface imperfections visible to the naked eye even after cutting.
6.2 Physical and chemical properties of rubber materials used for the manufacture of seals When tested in accordance with the methods detailed in clause 7, using standard test pieces, the material shall comply with the requirements given in table 3.
6.3 Physical and chemical properties of rubber material used for the manufacture of diaphragms
When tested in accordance with the methods detailed in clause 7, using standard test pieces, the material shall be in accordance with the requirements given in table 4.
7 Test methods
In addition to the conditions below reference should be made to table 5.
7.1 General
Thst pieces shall be cut from a sheet of material of (2 ± 0,2) mm or (6,3 ± 0,3) mm thickness as specified in the method of test. Measurements of thickness shall be carried out as specified in
ISO 4648.
The material shall be from the same compound formulation used to make the component, vulcanized under conditions which are comparable to those used in production.
7.2 Hardness
Five measurements shall be taken using the
micro-hardness test method on three test samples
of sheet material at a test temperature of
(23 ± 2) °C; as follows:
a) if the declared nominal hardness is 85 IRHD or less, use ISO 48;
b) if the declared nominal hardness is greater than 85 IRHD use ISO 1400.
7.3 TensIle strength and elongation at break
Measurements are carried out on six dumb-bell test
pieces, type 2, in accordance with the test method
given in ISO 37 at a test temperature of
(23 ± 2) °C.
7.4 CompressIon set
7.4.1 Three monobloek test piece discs of (13 ± 0,5) mm diameter and (6,3 ± 0,3) mm thickness shall be tested in accordance with the method gwen in ISO 815 and the following special conditions:
— compression: 25 % at (23 ± 2) °C;
— duration of test: (16802) h for seals
(24_5) h for diaphragms;
— test temperature: see table 5.
7.4.2 Three monoblock test pieces discs of (13 ±O5)mmdiameterand(6,3 ±O,3)mm thickness of materials having a classification of Al, Bi ….. El shall be tested in accordance with ISO 815 using the following special conditions:
— compression: 25 % at (23 ± 2) 00;
— duration of test: (7202) h;
— test temperature: (0 ± 1) °C;
— recovery time: (30 ± 3) mm.EN 549-1994 pdf download.