PLUMBING
Interceptor with sensing and alarm device.
Considerations When Selecting a Grease Interceptor
130
authorities have launched campaigns to clean up the water consumers are dumping into municipal pipelines. A feeling of responsibility for the environment has been growing in the general public. Businesses of every size are being tasked with “reducing their footprint” on society by containing and handling their waste on-site. Changes, options and advancements in grease interception and removal continue to grow. The problems caused by grease in
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sewer systems are well documented. Blockages can cause cleanup, repair or replacement costing in the millions of dollars. The obligation to properly contain grease is being pushed back to the source — the restaurants and establishments that produce it. Those who refuse to comply are being hit with penalties and fines, as local enforcement authorities increase inspection efforts. The solution is to equip an
establishment with a suitable grease interceptor and to make sure the operators understand their role in grease containment. Limitations, needs and circumstances vary by site, so where do you start when selecting an interceptor for a project? Below are some points to consider that will get you well on your way to specifying, recommending or installing the right solution.
Types (hydro-mechanical vs. gravity) A basic principle behind grease
separation in an interceptor is that
here seems to be a lot more talk about grease these days. Numerous local water quality
FOG (fats, oils, and grease) from a kitchen is “lighter” than water. It weighs about 1 lb. less per gallon. Interceptors that use only this
property difference for separation are known as gravity types. The grease- laden water must be given enough time in non-turbulent conditions for separation to occur. To accomplish this, gravity-type units must hold a very large volume and usually must have multiple chambers. They are typically installed underground, outside the establishment walls and are accessed for cleaning through manhole covers at ground level. Gravity-type units are identified by their holding volume in gallons. The other category of interceptors
is known as hydro-mechanical. These units increase separation performance through the use of flow control, air intake and baffles, which markedly decreases the time necessary to separate. This engineered approach allows hydro-mechanical units to be much smaller than their gravity-type counterparts for the same application. Two performance standards, PDI- G101 (Plumbing & Drainage Institute) and ASME A112.4.3, are widely used to test hydro-mechanical units and to ensure proper function at specified flow rates. Both types usually incorporate a
trapleg-style configuration at the outlet end so that, as new wastewater enters the inlet, the cleanest water near the bottom of the unit is pushed up and out to the pipe. Gravity-type units are traditionally too big to put inside the building and are direct- buried outside. If the walls of this unit are compromised due to loading, earth
BY BRIAN TUBAUGH
movement or material deterioration, the grease can seep directly into the ground. Hydro-mechanical units are typically much smaller and, therefore, can be installed inside the building and closer to the grease sources. Being indoors also reduces compromising risks, and the building itself acts a second layer of protection for the surrounding environment.
Location … location … location The two key considerations here are
the distance from the fixture(s) being served by the interceptor and accessibility. Recall the sewer system blockages
mentioned earlier. This was a length of pipe from grease-supplying establishments to a water treatment facility. The pipe inside a building from fixtures such as floor sinks, prep sinks and rinse sinks to the grease interceptor is like a miniature version of a sewer system pipe. The longer it is, the greater the risk that grease will congeal and cause a blockage. As a general rule, keep the interceptor as close to the fixtures being served as possible. If long runs are necessary, plan in periodic cleanouts for easy access later. Accessibility is very important. All
grease interceptors will need some human interaction. Even units with a grease removal device (GRD) need to be completely cleaned out periodically. Inevitably, waste that is heavier than water will enter the unit. If this is not removed, it will build up to the point of blocking the outlet and causing
e Continued on p 132
phc may 2011
www.phcnews.com
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