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Subchapter 1. Unfired Pressure Vessel Safety Orders
Article 6. Anhydrous Ammonia

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§508. Gaging Devices.

(a) A permanent dip pipe shall be installed in all tanks designed to be filled by volume, and shall be of such length that it will indicate when the tank is 86 1/2 percent full. The fixed dip pipe required in this order shall be permanently installed in the tank.

Each applicator container shall have a fixed liquid-level gage.

(b) Each tank filled by volume shall be equipped with a liquid level gaging device, such as a rotary gage, a slip tube, an automatic gage, a magnetic gage, or a series of fixed dip pipes, to show the liquid level in the tank at any time. This gaging device shall be in addition to the fixed dip pipe required in Section 508 (a).

A thermometer well shall be provided in all storage tanks over 1,200 gallons capacity not equipped with a fixed dip pipe, and in all transportation tanks.

(c) Liquid level gaging devices that require bleeding of the product to the atmosphere, such as rotary gages, dip pipes, or slip tubes, shall be so designed that the maximum opening of the bleeder valve is not larger than No. 54 drill size.

(d) Liquid level gaging devices shall be designed for a working pressure of not less than 300 psi ANS rating.

(e) Tubular-type gage glasses shall not be used.

(f) Each transportation tank exceeding 1,200 gallon capacity shall have a pressure gage installed with the dial graduated to approximately double the operating pressure but in no case less than 1.2 times the pressure at which the pressure relieving device is set to function.

Each farm vehicle tank over 250 gallons and each storage container shall be provide with a pressure gage graduated from 0 to 400 psi. Gages shall be designated for use in ammonia service.


1. Amendment filed 12-8-72 as procedural and organizational; effective upon filing (Register 72, No. 50).

2. Amendment of subsections (a), (b) and (f) filed 3-28-75; effective thirtieth day thereafter (Register 75, No. 13).

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