ASME A112.14.3-2000 pdf – CREASE INTERCEPTORS.
The average of the calibrated drainage flow rates for simultaneous discharge, as determined in this paragraph and in paras. 3.3.4. 1(c) and (d), shall be equal to or exceed by not more than 5% the proposed flow rate of the interceptor being tested. If the average flow rate so determined is less than the proposed flow rate of the interceptor, the flow control and/or vent orifice shall be enlarged and the check flow rate tests rerun and the calibrated drainage flow rates again computed until flow rates within the required limits are obtained. If the average of the calibrated drainage flow rates exceeds the proposed flow rate of the interceptor by more than 5%, the flow control and! or vent orifice shall he reduced in size and the above tests shall be repeated until an average flow rate is obtained that falls within the 5% limit stipulated above.
3.4 Skimming Procedure
The skimming procedure shall be initiated approximately 5 mm after the increment to be skimmed has discharged into the tank. A sheet metal hand baffle, slightly shorter than the width of the skimming tank and approximately 1 ft (0.30 m) in width, shall be employed to push all surfaced grease to one corner of the tank from which the layer of grease is readily skimmed by means of a rectangular pan. The mixture of water and grease thus removed shall be placed in a pail equipped with a drainage spigot. All grease shall be squeegeed from the baffle and pan. This process shall be continued until most of the visible grease has been removed from the surface of the water in the skim tank.
At this point, while the hand baffle previously used is allowed to cool, a second hand baffle shall be employed in the following manner:
The first 1 in. (25 mm) of the baffle plate shall he immersed at one end of the skimming tank and the baffle moved toward the opposite end, as before, to concentrate the now thin film of surfaced grease. The baffle shall be moved at a rate slow enough to prevent turbulence from drawing the accumulating grease below the baffle, and fast enough so that a minimum of grease will pass through the clearance space between the baffle and the tank walls. Upon reaching a point about 2 in. (50 mm) from the end of the tank, the baffle motion shall be slowed and, at the same time, the baffle shall the trapped grease. These motions shall be so regulated as to have the baffle submerged to within I in. (25 mm) of its top by the time it reaches the end of the last 2 in. (50 mm) of horizontal travel. The baffle shall then he removed from the water and moved, grease side up. to the pail where the adhering grease shall he squeegeed off and added to the previous contents. By 110w, the first baffle has cooled, and the above procedure is repeated using it. The baffles shall be used alternatcly until the amounts of grease collected in this manner arc less than 1% by visual observation.
Upon completion of the above skimming procedures, the water shall be drained from the bottom of the pail by means of the spigot. The pail shall then be placed over a gas flame and its contents heated until the residual water is brought to boiling temperature; that is, until bubbles of steam rise through the molten grease. The mixture shall then he poured from the pail into a separatory funnel, the pail shall be squeegeed out and the mixture shall be allowed to stand in the funnel for approximately 5 miii, at the end of which time the water is drawn off from the bottom of the funnel. The remaining liquid shall be permitted to separate for approximately 5 mm more and the water shall again be removed from the bottom of the funnel. The remainder shall be drained from the separatory funnel into one or more preweighed cans.