ASME A112.14.3-2018 pdf – Hydromechanical Grease Interceptors.
3.5 SkimmIng Procedure
The skimming procedure shall be initiated no less than S mm after the increment to be skimmed has discharged Into the tank. A sheet metal hand baffle, shghtly shorter than the width of the skimming tank and 12 in. (305 mm) in width shall be employed to push all surfaced grease to one corner at’ the tank from which the grease is readily skimmed by means of a rectangular pan. The mixture of water and grease thus removed shall be placed in a separatory funnel equipped with a dram cock. All grease shall be squeegeed from the baffle and pan. This process shall be continued until the visible grease has been removed from the surface of the water in the skim tank.
The first 1 In. (25 mm) of the baffle plate shall be immersed at one end of the skimming Lank and the baffle moved toward the opposite end, as before, to concentrate surfaced grease. The baffle shall be moved at a rate sufficient to prevent turbulence from drawing the accumulating grease below the baffle, and to minimize grease passing through the clearance space between the baffle and the tank walls.
Upon reachinga point 2 in. (51 mm) from the end of the tank, the baffle motion shall be slowed and simultaneously lowered to bring the cooler surface In contact with the trapped grease. The motion shall be executed such that the baffle is submerged to within I in. (25 mm) of its Lop upon reaching the end of the last 2 in. (Si mm) of horizontal travel.
The baffle shall then be removed from the water and moved, grease side up, to the separatory funnel where the adhering grease shall be squeegeed off and added to the previous contents. The baffle shall be used until the amounts of grease collected are less than 1% by visual observation.
The mixture shall be allowed to stand In the funnel for 5 mm, at the end of which time the water is drawn off from the bottom of the funnel. The remainder shall be drained from the separatory funnel into one or more preweighed cans.
The cans shall be cooled to solidify the grease, The cans may be placed In a freezer or refrigerator to expedite the cooling process. The solidified contents shall then be scraped and kneaded with a small putty knife, and the water thus worked from the mixture shall be poured off. If the quantity of water thus removed is greater than several drops, the heating and solidIfication process shall be repeated. When only a few drops of water are removed in this manner, the mixture shall be assumed to be completely dewatered and weights are taken for computation purposes.
5.1 GeneraL
The recommendations for sizing, installation, and maintenance of grease interceptors contained in this section arc based on input from PDI Table 1 is used for guideline purpocs and larger sizes are based on two pounds per gpm of rated flow,
5.2 Sizing
5.2.1 Sizing Considerations. Grease interceptors conforming to this Standard are designed to operate efficiently at their rated flow.
5.2.2 Size Symbots. It has been determined through the testing and rating procedure that ten different- sized interceptors are required for normal domestic. commercial, and institutional installations. These sizes are based an standard flow rates and grease retention capacity ratings for grease interceptors. (See Table 1.)
5.2.3 SizIng Procedure. Table 2 shows the basic standard formula in steps for sizing grease Interceptors to suit requirements ofspecific fixtures. An example of this sizing formula application is included to illustrate the steps. Table 3 is induded as a method for sizing grease interceptors utilizing maximum pipe capacity.