Page 309 - GoodyearEPIndustrialHose

APPENDIX c
Air &
Multipurpose
General Purpose
Heavy Duty
Push-on
Chemical
Transfer
Cleaning
Equipment
Food
Transfer
Washdown
Marine
Material
Handling
Abrasives
Bulk Transfer
Cement & Concrete
Mining
Petroleum
Aircraft Fueling
Dispensing
Dock
Transfer
Spray
Steam
Vacuum
Veyance
Water
Discharge
Suction &
Discharge
Washdown
Welding
Coupling
Systems
APPENDIX
307
ELECTRICAL RESISTANCE TESTS
FOR HOSE AND HOSE ASSEMBLIES (continued)
GENERAL INFORMATION
used the electrode contact area shall be completely wetted and shall remain so until the end of the test. The conductive liquid
shall consist of:
• Anhydrous polyethylene glycol of relative molecular mass 600: 800 parts by mass
• Water: 200 parts by mass
• Wetting agent: 1 part by mass
• Potassium Chloride: 10 parts by mass
When the test procedure calls for contact with the hose tube, it is preferable to use a copper plug of external diameter equal to
or slightly greater than the hose ID or a steel hose stem, coated with the conducting liquid, and pushed 25 mm (1”) into the
hose. An alternative for 50 mm (2”) and above hose would be to apply the conductive silver lacquer onto the hose ID, then insert
the plug or hose stem. The electrical leads from the test instrument shall be clean and they should make adequate contact with
the metallic copper foil and/or copper plugs/hose stems.
5.0 Preparation and Cleaning for Test:
The surfaces of the hose shall be clean. If necessary, the hose surface may be cleaned by rubbing with Fuller’s earth
(magnesium aluminum silicate) and water, followed by a distilled water rinse, and allowing the hose to dry in a non-
contaminating environment. Do not use organic materials that attack or swell the rubber, and do not buff or abrade the
test surfaces.
The surface of the hose shall not be deformed either during the application of the contacts or during the test. When using test
pieces, the supports shall be outside the test length. When using a long length of hose, the hose shall be uncoiled and laid out
straight on polyethylene or other suitable insulating material. Care should be taken to ensure that the hose is insulated from
any electrical leakage path along the length of the hose.
6.0 Test Conditions:
For lab testing, the hose or hose assemblies shall be conditioned for at least 16 hours at +23° C ± 2°C (73.4°F ± 3.6°F) with a
relative humidity not to exceed 70%. However, it is permissible, by agreement between the supplier and the customer, to use
the conditions prevailing in the factory, warehouse, or laboratory, provided that the relative humidity does not exceed 70%.
7.0 Test Pieces:
Prepare three test pieces approximately 300 mm (12”) long from samples taken at random from a production run or lot.
Condition the test pieces per section 6.0.
Place the test piece on blocks of polyethylene, or other insulating material, to provide a resistance of greater than 1011 O
between the test piece and the surface on which the blocks are supported. Ensure that the leads from the instrument do not
touch each other, the hose, or any part except the terminal to which each is connected.
Avoid breathing on the test surfaces and thus creating condensation that may lead to inaccuracies.
8.0 Procedure for hoses with conducting tube:
Apply the electrodes as specified to the inside surface of the hose at each end of the hose. The edge of the electrode plug shall
be coincident with the end of the hose. When using a conductive liquid, care shall be taken to avoid creating a leakage path
between the tube and the reinforcement or cover of the hose.
Apply the metal contacts to the electrodes.
Apply the test voltage (9V) and measure the resistance 5 seconds ± 1 second after the voltage is applied.
Note: In previous editions of the Hose Handbook, this method was referred to as the Plug Method.
9.0 Procedure for hose with conducting cover:
Apply the electrodes as specified to the outer circumference of the hose at each hose end. See Figure 6-1.
Ensure that contact is maintained with the electrodes around the circumference and that the contact pieces are sufficiently
long enough for the two free ends to be held securely by a tensioning clip (see Figure 6-1) such that the fit of the electrodes is
as tight as possible.
Apply the metal contacts.
Apply the test voltage (9V) and measure the resistance 5 seconds ± 1 second after the voltage is applied.