Page 308 - 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
306
ELECTRICAL RESISTANCE TESTS
FOR HOSE AND HOSE ASSEMBLIES
GENERAL INFORMATION
1.0 Purpose:
This procedure specifies methods for performing electrical resistance tests on rubber and/or plastic hose and hose assemblies.
2.0 Scope:
These procedures are intended to test electrical conductive, antistatic and nonconductive (insulating) hoses, along with
electrical continuity or discontinuity between fittings.
3.0 Definitions:
3.1 Antistatic Hose - Antistatic hose constructions are those that are capable of dissipating the static electricity buildup that
occurs during the high velocity flow of material through a hose.
3.2 Conductive Hose – Conductive hose constructions are those that are capable of conducting an electrical current.
3.3 Direct Current (DC): Flow of electrical current in one direction at a constant rate.
3.4 Electrical Conductivity: A measure of the ease with which a material is capable of conducting an electrical current.
Conductivity = 1/Resistance.
3.5 Electrical Resistance: Property of an object to resist or oppose the flow of an electrical current.
3.6 Non-Conductive (Insulating) Hose: Non-conductive hose constructions are those that resist the flow of electrical current.
3.7 Ohm’s Law: The electrical current, I, is equal to the applied voltage, V, divided by the resistance, R. In practical terms, the
higher the electrical resistance at a constant voltage, the lower the electrical current flow through an object.
3.8 Ohm: The amount of resistance that limits the passage of current to one ampere when a voltage of one volt is applied to it.
4.0 Apparatus:
4.1 Test Instruments: All test instruments shall have a gauge reliability and reproducibility (R&R) of less than 30%. Some
instruments made to measure high electrical resistance may have an internal protection circuit built in which will cause test
errors in the less than one megohm range.
During the test, no more than 3 watts (W) shall be dissipated in the specimen, to prevent erroneous results due to effects of
temperature. The power dissipated shall be determined by the square of the open-circuit voltage divided by the measured
resistance, see formula 1 (Power Dissipation).
To determine the electrical resistance of non-conductive hose, the test should be made with an instrument designed
specifically for measuring insulation resistance, having a nominal open-circuit voltage of 500 Volts D.C., or with any other
instrument known to give comparable results. For measuring electrical discontinuity, a 1,000 Volt D.C. source may be used
instead of a 500 Volt D.C. source.
For hoses with a conductive tube or cover, the resistance values obtained may vary with the applied voltage, and errors may
occur at low-test voltages. As a starting point, an ohmmeter (9 volts) can be used. For tests requiring measurement of electrical
continuity between end fittings or through continuous internal or external bonded wires, the instrument used shall be an
ohmmeter (9 volts).
4.2 Electrodes and Contacts: When the test procedure calls for contact with the hose cover, electrodes shall be formed
around the outer circumference of the hose as bands 25 mm +2 mm, 0 mm (1” +1/16”, 0”) wide by applying silver
lacquer/conductive liquid and metallic copper foil tape (i.e. 3M Scotch Brand) as shown in Figure 6-1. When a conductive
silver lacquer (i.e. Colloidal Silver Liquid is available from Ted Pella, Inc. catalogue # 16031) is used, the surface
resistance between any two points on a sample of the dried film shall not exceed 100 Ω. When a conductive liquid is
Warning:
Hydraulic hoses used on power and telephone mobile equipment should be tested to SAE
100R8 requirements.
(Voltage)2
1) Power Dissipation =
Resistance in ohms