Transcript Slide 1

Types, Sizing, Application and
Maintenance
A Brief Overview
Presented by Max Weiss, Consultant
Jay R. Smith Mfg. Co., Inc.
Nomenclature: Traps vs. Interceptors
Interceptor Subtypes
1
2-6
Hydromechanical Grease Interceptors (GIs)
Grease Recovery Devices (GRDs)
Fats, Oils and Grease (FOG) Disposal Systems
Gravity Grease Interceptors
Sizing
7-11
Hydromechanical GIs – based on pipe size
Gravity GIs – based on pipe size
Hydromechanical GIs – based on fixture capacity
Gravity GIs – based on fixture capacity
Application
Maintenance
12
13-23
Pros/Cons by Type
Conclusion
24
Nomenclature clarification
►
Recent changes in codes and standards to clarify mixed terms
►
“Trap” has been eliminated in ASME Standards, UPC, CSA and
(pending) IPC
►
“Interceptor” is deemed to be a more inclusive term
►
“Interceptor” allows for a more precise distinction between
devices
►
First official adoption was by IAPMO during its comprehensive
rewrite of Chapter Ten (10) of the Uniform Plumbing Code.
1
Hydromechanical Grease Interceptors (GIs)
Grease Recovery Devices (GRDs)
Fats, Oils and Grease (FOG) Disposal Systems
Gravity Grease Interceptors
2
Definition
Hydromechanical Grease Interceptor [Plumbing Drainage Institute]
3
Definition
Grease Removal Device [Plumbing Drainage Institute]
4
Definition
FOG Disposal System [Plumbing Drainage Institute]
5
Definition
Gravity Interceptor [Plumbing Drainage Institute]
6
UPC, Chapter 10, Appendix H Limitations
Drainage Fixture Units [DFU] Misconception
Maximum Flow Sizing
Grease Interceptor Sizing Truths
7
Pipe Diameter
2.0
Slope*
GPM** Nominal Interceptor Rating
.120
13.75
15gpm
.240
19.44
20gpm
3.0
.120
41.49
50gpm
.240
58.67
75gpm
4.0
.120
88.93
100gpm
.240
125.77
125gpm
5.0
.120
162.46
175gpm
.240
229.75
250gpm
6.0
.120
265.50
275gpm
.240
375.47
400gpm
8.0
.120
575.81
600gpm
.240
814.32
825gpm
* Inches drop per foot of run.
**Based on Mannings formula with friction factor N=.012 as published by Cast Iron
Soil Pipe Institute (CISPI)
Or, actual fixture volume plus hydrant capacity, divided by drain period
whichever is less.
8
Pipe Diameter
2.0
3.0
4.0
5.0
6.0
8.0
Slope*
.120
.240
.120
.240
.120
.240
.120
.240
.120
.240
.120
.240
GPM** Nominal Interceptor Volume***
13.75
500 gal.
19.44
750
41.49
1,250
58.67
1,800
88.93
2,750
125.77
4,000
162.46
5,000
229.75
7,000
265.50
8,000
375.47
11,500
575.81
18,000
814.32
25,000
* Inches drop per foot of run.
**Based on Mannings formula with friction factor N=.012 as published by Cast Iron Soil Pipe
Institute (CISPI)
***Based on 30 min. retention (Metcalf & Eddy) rounded to nearest volume of 250 gal. increments.
Or, actual fixture volume plus hydrant capacity, divided by drain period X 30
whichever is less.
9
Calculation of fixture capacity:
[Length] X [Width] X [Depth] / [231] = Gallons X [.75 fill factor] / [Drain Period (1 or 2)]
Add hydrant capacity (gpm supply);
Add dishwasher, water wash hood at manufacturer ratings.
EXAMPLE:
Fixture Compartment Size,
in.
Compartments
Load,gal
Recommended Interceptor Size,
One-Minute
Drain
24x24x12
2
44.9
50
Two-Minute
Drain
25
The selection listed is based on application of the sizing formula above.
10
Multiply the result of either "Fixture Capacity" or "Pipe
Size" (above) by 30 to reflect required retention time.
EXAMPLE
35 gpm X 30 = 1,050 gal. capacity.
This sizing method is the "Uniform Interceptor Sizing“ – for
obvious reasons.
All parameters are uniformly applied to the computation of
GPM from any given facility to any given interceptor.
11
Why is an interceptor required?
Pretreatment as the prime consideration
Administrative convenience versus concern for water
quality
Versatility of installation, proximity to FOG source,
decreased maintenance frequency
12
Hydromechanical GIs
Pros
Located near the FOG source
Usually small compared to gravity units
Can be cleaned with conventional dip and bucket or
small vacuum units
Cons
More convenient to ignore than to clean
Will continue to flow water even after they no longer
function as an interceptor
Rarely have third party maintenance verification
13
Grease Removal Devices
Pros
Located near the FOG source
Automatically remove FOG for proper disposal
Less maintenance required
Cons
More expensive initially than hydromechanical GIs
Require solids separation preceding the waste stream
Have moving parts and are prone to mechanical problems
14
FOG Disposal Systems
Pros
Require less maintenance than GRDs – some requiring only
annual service
Can be quite small relative to the size flow capable of being
treated
Have the most rigorous performance testing and usually
provide the cleanest effluent
Remove solids with the use of a solids interceptor
Cons
More expensive than hydromechanical GIs and most GRDs
Require attention to solids interceptors – neglect can affect
performance of some units
Frequently foreign to local jurisdictions
15
Gravity Interceptors
Pros
More recognized and usually easier to get approved by local
authorities
Require little or no attention from the facility operator
Compatible with third party maintenance
Cons
Significantly more difficult and expensive to install
The most frequently improperly sized interceptors
The least efficient in terms of FOG separation
Prone to hydrogen sulfide generation and accelerated
corrosion
Falsely believed to be capable of FOG storage exceeding 30
days
Expensive to service at proper frequency and
thoroughness
16
FOG in Lift Station
17
Corrosion Interior Concrete Interceptor
18
Other Lines in Lift Station
19
Combined Sewer Clogged with Grease
20
Grease in PVC Pipe
21
Channel in Grease Layer
22
Bag Type Interceptor
23
Rarely is the best interceptor for the job selected.
Even more rarely is the selected interceptor sized
correctly.
Even rarer still is the interceptor that is installed
correctly.
Nonexistent is the interceptor that is the right interceptor
for the job, sized properly, installed correctly AND
operated and maintained as the manufacturer intended
with the intent of producing the highest quality effluent
possible.
24