A presentation by Rand Ackroyd, of the Plumbing and Drainage Institute, sorting out grease myths and facts. For more information, please visit www.jrsmith.com

1. Presented by Rand Ackroyd
Copyright PDI 2008

2. Plumbing and Drainage Institute
• The Plumbing and Drainage Institute
(PDI) was formed in 1949.
• The organization developed the original
performance requirements for Grease
Interceptors (Hydromechanical Grease
Interceptors) PDI G101.
Copyright PDI 2008

3. Plumbing and Drainage Institute
Our objectives:
– Advancement of Engineered Plumbing
Products
– Publicity/Public Relations
– Research
– Publish Standards
– Education
Copyright PDI 2008

4. GREASE…
How Bad Can It Be?

5. • Myth: If grease is not used in food
preparation a grease interceptor is not
needed.
• Fact: Grease is not the only problem. The
overall problem is FOG (Fats, Oils and
Grease). These materials alone or in
combination will result is sewer blockages.
Copyright PDI 2008

6. • Myth: Choosing a larger size grease
interceptor will result in a greater grease
removal efficient.
• Fact: When grease interceptor has been
sized properly to the anticipated maximum
flow using a grease interceptor with a larger
flow capacity will not increase grease
removal efficiency.
Copyright PDI 2008

7. • Myth: The larger the grease storage, the
more efficient the interceptor.
• Fact: Grease must be separated from the
waste water before it can be stored.
Storage capacity and grease removal
efficiency are not related.
Copyright PDI 2008

8. • Myth: The grease must cool and harden to
separate from the waste water.
• Fact: Grease interceptors separate based on
the difference in specific gravity of FOG and
water. Liquefied grease floats just as well as
solidified grease. Grease is lighter than
water.
Copyright PDI 2008

9. • Myth: Hot water will melt the grease and
wash the grease through the interceptor.
• Fact: All hydro mechanical grease
interceptors are tested for grease removal
efficiency with 150°F water.
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10. • Myth: Once the grease is captured in the
interceptor, it will remain captured in the
interceptor as long as the interceptor is not
yet 25% full.
• Fact: Because the grease (FOG) is
contaminated with food particles and the
interceptor is a breeding ground for bacteria,
the FOG can be broken down, exit the
interceptor and create blockages
downstream.
Copyright PDI 2008

11. • Myth: Over sizing an interceptor cannot
hurt.
• Fact: Over sizing an interceptor relative to
actual flow is a problem. It can result in the
generation of hydrogen sulfide gas that can
convert to hydrochloric acid. Both metal
and concrete structures downstream have
suffered severe structural damage from
this acid.
Copyright PDI 2008

12. • Myth: With the change to healthier cooking
oils, there is less of a FOG problem.
• Fact: Cooking oils that are healthier for you
are not healthier for the drainage system.
They are all polar hydrocarbons. In fact,
some of the new alternative cooking oils
with specific gravities closer to water will
be harder to capture from the wastewater.
Copyright PDI 2008

13. • Myth: When the grease interceptor is full,
the drain line will stop flowing.
• Fact: Water will continue to flow even when
the FOG in the interceptor is at capacity.
Additional grease in the wastewater will
simply flow right through the interceptor.
Grease interceptors must be either
manually or electronically monitored.
Copyright PDI 2008

14. • Myth: Grease does not clog plastic pipe
• Fact: Grease can create blockages all al
drain pipe materials.
Copyright PDI 2008

16. Thank You For Your Time!
Copyright PDI 2008