Grease Interceptors
Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
Showing changes from Rev 5
to Rev 6
in Grease Interceptors.
---
title: Grease Interceptors
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# Interceptor Type Selection {toc}
−## General {toc}
+## The two principal interceptor families serve different scales and installation conditions. {note}
−### The two principal interceptor families serve different scales and installation conditions. {note}
+## The grease interceptor type shall be specified, selected to match the facility's flow scale and installation conditions.
```datasheet
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```
−### Hydromechanical grease interceptors (HGI) are compact, flow-rated devices that separate grease by buoyancy and baffling at relatively high flow velocity; they install at or near the point of use, indoors, and are rated by flow rate and grease capacity. {note}
+## Hydromechanical grease interceptors (HGI) are compact, flow-rated devices that separate grease by buoyancy and baffling at relatively high flow velocity; they install at or near the point of use, indoors, and are rated by flow rate and grease capacity. {note}
−### Gravity grease interceptors (GGI) are large in-ground or exterior vaults that separate grease and solids by quiescent retention over a defined retention time; they are sized by liquid volume and serve an entire kitchen or multiple establishments. {note}
+## Gravity grease interceptors (GGI) are large in-ground or exterior vaults that separate grease and solids by quiescent retention over a defined retention time; they are sized by liquid volume and serve an entire kitchen or multiple establishments. {note}
−### Automatic grease removal devices (GRD) are hydromechanical interceptors fitted with a powered skimmer that continuously or periodically removes accumulated grease into a collection container, reducing the manual cleaning burden. {note}
+## Automatic grease removal devices (GRD) are hydromechanical interceptors fitted with a powered skimmer that continuously or periodically removes accumulated grease into a collection container, reducing the manual cleaning burden. {note}
−### The selection between HGI and GGI is driven by the connected load, the available indoor space, the local FOG ordinance, and the sewer authority's preference; many jurisdictions mandate an exterior gravity interceptor of a minimum volume for any establishment with a commercial kitchen, and permit hydromechanical interceptors only for limited fixture counts or for tenant build-outs where an exterior vault is impractical. {note}
+## The selection between HGI and GGI is driven by the connected load, the available indoor space, the local FOG ordinance, and the sewer authority's preference; many jurisdictions mandate an exterior gravity interceptor of a minimum volume for any establishment with a commercial kitchen, and permit hydromechanical interceptors only for limited fixture counts or for tenant build-outs where an exterior vault is impractical. {note}
−### The Contractor shall confirm the permitted interceptor types with the sewer authority before selection.
+## The Contractor shall confirm the permitted interceptor types with the sewer authority before selection.
## Application Guidance {toc}
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### Automatic grease removal devices are appropriate where space is limited but a high cleaning frequency is undesirable, such as in high-volume kitchens where manual cleaning of a small hydromechanical unit would otherwise be required several times per week; their higher first cost and the maintenance of the powered skimmer are offset by reduced manual labor and more consistent effluent quality. {note}
−# Sizing {toc}
+# Interceptor Sizing Method {toc}
−## General {toc}
−
```datasheet
label: Sizing Method
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```
−### The interceptor shall be sized by the method required by the local FOG control ordinance.
+## The interceptor shall be sized by the method required by the local FOG control ordinance.
−### Where the ordinance does not prescribe a method, the interceptor shall be sized by the method in the adopted plumbing code.
+## Where the ordinance does not prescribe a method, the interceptor shall be sized by the method in the adopted plumbing code.
−### The Contractor shall not reduce the interceptor size below the size the ordinance or code requires, and shall submit the sizing calculation for review.
+## The Contractor shall not reduce the interceptor size below the size the ordinance or code requires, and shall submit the sizing calculation for review.
−### The hydromechanical unit shall be matched to the connected load, not arbitrarily enlarged.
+## The hydromechanical unit shall be matched to the connected load, not arbitrarily enlarged.
−### Oversizing a hydromechanical interceptor degrades performance, because at flows well below the rated flow the unit loses the velocity and baffling action it relies on; gravity interceptors, by contrast, benefit from generous volume because retention time and storage both improve with size. {note}
+## Oversizing a hydromechanical interceptor degrades performance, because at flows well below the rated flow the unit loses the velocity and baffling action it relies on; gravity interceptors, by contrast, benefit from generous volume because retention time and storage both improve with size. {note}
−## Hydromechanical Interceptor Flow Rate and Grease Capacity {toc}
+# Hydromechanical Interceptor Flow Rate and Grease Capacity {toc}
```datasheet
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```
−### Hydromechanical interceptors shall be rated by flow rate in gallons per minute (GPM) and by grease storage capacity in pounds (lb), determined by test in accordance with PDI G101 or ASME A112.14.3.
+## Hydromechanical interceptors shall be rated by flow rate in gallons per minute (GPM) and by grease storage capacity in pounds (lb), determined by test in accordance with PDI G101 or ASME A112.14.3.
−### The rated flow shall equal or exceed the computed drainage flow rate from the connected fixtures, determined either from the fixture drain rate or from the drainage fixture unit load converted to GPM by the method in the adopted code.
+## The rated flow shall equal or exceed the computed drainage flow rate from the connected fixtures, determined either from the fixture drain rate or from the drainage fixture unit load converted to GPM by the method in the adopted code.
−### Where the connected fixtures have no assigned drainage fixture unit value, the flow rate shall be computed from the known fixture discharge rate.
+## Where the connected fixtures have no assigned drainage fixture unit value, the flow rate shall be computed from the known fixture discharge rate.
−### The grease storage capacity rating shall comply with the minimum ratio established by the rating standard, which requires not less than 2 pounds of grease storage capacity for each gallon per minute of rated flow.
+## The grease storage capacity rating shall comply with the minimum ratio established by the rating standard, which requires not less than 2 pounds of grease storage capacity for each gallon per minute of rated flow.
−### The grease capacity determines how long the unit can operate between cleanings before separation efficiency falls; a 20 GPM unit therefore provides at least 40 lb of grease capacity, a 50 GPM unit at least 100 lb, and a higher grease capacity at a given flow rate extends the maintenance interval and is preferred where the cleaning interval is a concern. {note}
+## The grease capacity determines how long the unit can operate between cleanings before separation efficiency falls; a 20 GPM unit therefore provides at least 40 lb of grease capacity, a 50 GPM unit at least 100 lb, and a higher grease capacity at a given flow rate extends the maintenance interval and is preferred where the cleaning interval is a concern. {note}
−## Gravity Interceptor Liquid Volume {toc}
+# Gravity Interceptor Liquid Volume {toc}
```datasheet
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```
−### Gravity grease interceptors shall be sized by liquid volume to provide the retention time required by the adopted code or FOG ordinance.
+## Gravity grease interceptors shall be sized by liquid volume to provide the retention time required by the adopted code or FOG ordinance.
−### The minimum liquid volume and the number of compartments shall not be less than the values required by the governing ordinance.
+## The minimum liquid volume and the number of compartments shall not be less than the values required by the governing ordinance.
−### The minimum liquid volume of a gravity grease interceptor shall be not less than 500 gallons unless the governing ordinance permits a smaller vault.
+## The minimum liquid volume of a gravity grease interceptor shall be not less than 500 gallons unless the governing ordinance permits a smaller vault.
−### Gravity interceptors shall have not fewer than two compartments separated by a baffle wall, with the inlet to the first compartment and the outlet from the second.
+## Gravity interceptors shall have not fewer than two compartments separated by a baffle wall, with the inlet to the first compartment and the outlet from the second.
−### The Uniform Plumbing Code recognizes a 30-minute retention time, and the UPC Appendix H method and the National Precast Concrete Association sizing procedure compute the required liquid volume from the drainage fixture units or the known fixture flow rate multiplied by the retention time, with adjustments for the establishment type and operating hours; many ordinances establish a 750-gallon or 1000-gallon minimum for any commercial kitchen. {note}
+## The Uniform Plumbing Code recognizes a 30-minute retention time, and the UPC Appendix H method and the National Precast Concrete Association sizing procedure compute the required liquid volume from the drainage fixture units or the known fixture flow rate multiplied by the retention time, with adjustments for the establishment type and operating hours; many ordinances establish a 750-gallon or 1000-gallon minimum for any commercial kitchen. {note}
−### The two-compartment arrangement allows grease to rise and solids to settle in the first compartment while the second compartment provides a quiescent zone that polishes the effluent before discharge. {note}
+## The two-compartment arrangement allows grease to rise and solids to settle in the first compartment while the second compartment provides a quiescent zone that polishes the effluent before discharge. {note}
# Hydromechanical Grease Interceptors {toc}
−## Construction {toc}
+## Body Construction, Material, and Location {toc}
```datasheet
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## The warranty shall not limit or replace the Contractor's obligation to comply with all applicable code and FOG ordinance requirements and the requirements of this standard.