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PROPERTY PROCEDURE VALUE <br /> 1 Aged (7 days @ 75°F, 0.13 <br /> 2 50% R.H.) <br /> • 3 Flammability Characteristics <br /> 4 Flame Spread ASTM-E-84 less than 25 <br /> 5 Smoke Developed 200 to over 500 depending <br /> on thickness <br /> ' 6 <br /> 7 C. After the insulation has been sprayed and allowed to cure, a latex mastic coating shall be <br /> e applied to the surface of the insulation in such a manner as to seal the insulation from the <br /> 9 outside environment. A minimum of two coats shall be required. Standard color shall be <br /> 10 white. <br /> 11 <br /> 12 D. The insulation shall be a minimum of 2 inches thick over the exposed surface of the tank. <br /> 13 <br /> 14 <br /> 15 2.04 ELECTRICAL HEAT TRACING <br /> 16 <br /> 17 A. Provide an electrical heat tracing system for the sodium bisulfite tank as specified below. <br /> 18 <br /> 19 1. Parallel resistance type constant watts per foot electrical heater cable which shall <br /> 20 include the following features: <br /> 21 <br /> 22 a. Not more than 8 watts per linear foot to insure that the heater cable or the tank <br /> 23 wall will not exceed 150 degrees F in the event that the thermostat fails in the <br /> 24 closed position. (The 8 watts per foot maximum might be lower depending on <br /> 25 tank wall thickness, maintenance temperature, and the product in the tank.) <br /> 26 <br /> 27 b. Not less than 12 gauge copper bus wires. <br /> 28 <br /> 29 c. 38 gauge nickel chromium resistance wire. Contact with the bus wire shall be <br /> 30 assured by being embedded into the extruded outer insulation, and locked into <br /> 31 place by a special 'rip cord' feature of the inner insulation. <br /> 32 <br /> 33 d. Heater cable insulation shall be made of pressure extruded Santoprene (trademark <br /> 34 of Monsanto) thermoplastic rubber to insure flexibility, ease of installation, <br /> 35 resistance to moisture, chemicals and mechanical abuse. <br /> 36 <br /> 37 e. Heater cable width shall not be less than 3/S' to insure that the density of the <br /> 38 watts output will not cause scorching or softening of the tank wall or damage the <br /> 39 heater cable insulation. <br /> 40 <br /> 41 f. Heater cable shall be attached using 2' wide aluminum tape applied along the <br /> 42 entire length of the heater cable to insure adequate thermal conductance. <br /> 43 <br /> 44 g. Heater cable shall be installed in a spiral fashion incorporating a short wave or <br /> 45 'hump' at a regular interval to ensure that the heater cable shall not be stretched <br /> 46 or snapped in the event of tank wall expansion. <br /> 47 <br /> 48 h. The heater cable shall have non-heating leads long enough to reach the <br /> CHEMICAL STORAGE TANKS <br /> 081294 13416-3 <br /> 1 <br />