tent use of heating coils could result in excess vapor generation and tank overpressure. Vents
should be adequate to accommodate flow rates during unloading. Vapor controls such as conserva-
tion vents, relief valves, floating roofs, scrubbers, carbon absorbers or flares may be required for
safety, environmental or odor control purposes. A nitrogen blanket is the preferred atmosphere.
Unloading by nitrogen pressure is recommended. Pumping is satisfactory with an inert purge on the
transferring vessel and the storage tank. Never use air or oxygen for pressuring.
Piping of mild or stainless steel; flanged construction is recommended for 2" and larger sizes with
valves of mild steel, cast iron or stainless steel. Flanges in pipelines carrying DMS should be electri-
cally jurnpered so as not to rely on the bolts as conductors. The piping should be designed so that
liquid velocities do not exceed 10 feet per second and the entry of DMS into tanks should be at the
bottom through a dip tube to avoid static electricity. Do not allow DMS to fall through a vapor space.
Hose of stainless steel wire covering either a Teflon liner or a stainless steel bellows is preferred.
Couplings: Hose fittings should be non-sparking brass or aluminum; an Acme type screw on LPG
type fitting is an option.
Gaskets and O-rings should be of Teflon
Pumps may be mild steel or stainless steel with mechanical seals to avoid leaks.
Electrical equipment should be suitable for a Class I hazardous location (Article 500 of the National
Electric Code). Specific installations determine whether Division 1 (normally hazardous) or Division 2
(potentially hazardous) location is indicated.
BIBLIOGRA PHY
1. R. J. Herschler; U. S. Patent 3,023, 074, Feb. 27, 1962.
2. F. Siclari and A. Bellano; Italian Patent 508, 513, Jan. 10, 1955.
3. L. K. Frevel and L. J. Kressley; U. S. Patent 3,075,024, Jan. 22, 1963.
4. R. A. Stewart and E. Lasis; U. S. Patent 3,196,143, July 20, 1965.
5. H. B. Welirnan; U. S. Patent 3, 236, 046, Feb. 22, 1966.