MIFAB, Inc.
CHAPTER 10
CHAPTER 10
INTERCEPTORS
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INTERCEPTORS
MIFAB, Inc.
CHAPTER 10
INTERCEPTORS
The purpose of an interceptor is to separate and store the materials from the water
passing through it. They are installed on the drain line coming from a device that can have
particles in the water that need to be removed prior to entering the public drain system. This is
regulated by local codes to minimize the maintenance on the public drain system.
Clogged Pipes with Grease and Oils
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A. Interceptor Components
a) Body and Lid are Acid Resistant Epoxy (ARE) Coated inside and out.
b) Lids are 7ga. Diamond plate mild steel.
i. –HD option lids are reinforced with angle iron on the underside of the lid.
c) The Lid Bolts (MI-BOLT) are 5/8-11UN flanged bolts with neoprene washer.
i. The head of the bolts are covered with a plastic cap (MI-CAP) to minimize
the chance of tripping.
d) Crossbars fit into the crossbar brackets and are held in with cotter pins. The
crossbar has a nut welded to the top to hold down the Lid with the Lid Bolts.
i. The nut is welded on top of the crossbar to allow the lid to be removed
incase the crossbar or nut weld rust.
e) The Body is made with ½” legs on the ends to allow the interceptor to rest on
the feet. This elevates the bottom of the interceptor from the wet ground or
floor to prevent corrosion.
f) Sewer Gas Stopper and Deep Seal Trap are located on the inside of the
interceptor at the outlet.
i. The deep seal trap takes the water from the bottom of the interceptor.
ii. The Sewer Gas Stopper doesn’t allow sewer gas from entering the
interceptor and possibly the upstream drain line.
g) Internal Baffles direct the path of the waste water entering the interceptor.
i. The baffles are removable to allow easy access when cleaning.
h) Interceptors either have an external or internal flow control.
i. Regulates the amount of flow going through the interceptor.
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B. Grease Interceptors
a) The purpose of a grease interceptor is to trap and store the suspended
grease from the water passing through it. They are usually connected to
kitchen sinks, floor drains, and other plumbing fixtures in restaurants, hotels,
and institutions that discharge grease laden waste water. MIFAB’s grease
interceptors operate on the principle of separation by floatation.
b) Function of the interceptor.
i. Waste water enters the interceptor hitting the baffle. The baffle keeps
the water calm inside the interceptor. Allowing the grease and oil to
properly separate.
ii. The grease and oil separate in the main part of the interceptor.
iii. The sludge stopper retains any sediment that sinks from clogging the
deep seal trap.
iv. The water exiting the interceptor is taken from the bottom of the deep
seal trap.
c) The interceptor always has water in it up to the bottom of the inlet and
outlet. The capacity of the interceptor allows time for the water and grease
to separate.
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i.
Grease is less dense than water and the grease separates from the water
as it cools. The grease and oils will float to the top of the water. The
grease and oils will remain on the top of the water until it is serviced.
d) Flow Controls
i. External flow controls have the same
connection as supplied on the interceptor with
an internal orifice hole calibrated to allow the
proper flow to the interceptor.
1. External flow controls are to be installed
prior to the interceptor.
2. It also has a vent connection that is to be connected to the drain pipe
vent system.
a. The vent connection allows air to enter the drain pipe and creates
a smoother flow of the drain water entering the interceptor.
ii.
Internal flow controls are located on the
inside of the interceptor at the inlet.
a. They are a piece of stainless steel
with the calibrated orifice hole to
allow the proper flow to the
interceptor.
e) Sizing
i. Sizing of the required interceptor is determined by the maximum amount
of flow (GPM) through the interceptor.
ii. The calculations are per Plumbing and Drainage Institute (PDI) G-101
standard.
1. Calculate the volume of all the fixtures to be served by the grease
interceptor.
a. Three compartment sink with 15” x 10” x 24” sinks
i. 15” x 10” x 24” = 3600in^3 x 3 = 10,800in^3
b. Convert the volume to gallons.
i. Divide the calculated volume by 231
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ii. 10,800in^3 / 231 = 46.75 gallons
c. Multiply calculated gallons by average fixture capacity. (75%)
i. 46.75 gallons * 75% = 35.06 gallons
d. This gives the required gallons of flow in a 1 minute drain time.
i. 35.06 gallons / 1 minute = 35 GPM
ii. 35GPM capacity interceptor is required.
f) MI-G and MI-G-L Series
i. All come with an external flow control (FLC).
ii. MI-G-L Series is designed to have a low rough in to better fit in restricted
spaces.
iii. All additional options are listed in the Price Book.
g) XL-MI-G Series
i. Larger capacity interceptors.
ii. All come with an internal flow control.
iii. All additional options are listed in the Price Book.
h) MI-G-SS Series
i. Same capacity and design as the MI-G Series constructed out of 304
stainless steel.
ii. All come with an external flow control (FLC).
iii. All additional options are listed in the Price Book.
i) MI-G-SD Series
i. All units come with a grease draw-off valve.
1. It allows the grease to be removed from the unit without removing
the lids.
j) MI-G-SDH Series
i. Semi automatic draw off grease interceptor.
ii. The top port is plugged and can be opened to attach a hose for grease
drainage.
iii. How to operate the interceptor when cleaning.
1. Close the ball valve on the outlet side of the interceptor.
2. Remove the drain plug on the lid and connect the hose.
3. Run hot water into the interceptor. The how water will liquefy the
grease and push it out of the drain hose.
4. The interceptor is clean once the water coming out of the drain hose
is clear.
5. Remove the hose and reinstall the cap. Open the ball valve and the
unit is ready to be put back in service. Occasional internal cleaning is
still necessary to remove sediment and debris.
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C. Cover Shrouds
a) MI-CS Series
b) Cover Shrouds provide support for the interceptor and adjustability of the
inlet and outlet dimensions to match drainage piping where necessary.
c) The shroud can be set in the slab at the time of pouring.
d) The shroud is secured and suspended in the slab by its anchoring flanges.
e) The interceptor is easily accessible for cleaning and inspection by simply
removing the cover that sits flush with the floor.
D. Oil Interceptors
a) Oil interceptors are designed for use in drain lines where oils and sediment
are found. These drain lines may be from areas in parking garages, machine
shops, service stations, aircraft hangars, industrial and manufacturing areas.
b) The oil interceptors are designed to protect against water pollution by
preventing oils and sediment in waste water entering the drain lines.
c) The MI-O and MI-O-HU Series have a draw-off valve that allows the
intercepted oil to automatically be placed in a storage device.
i. The oil draw-off instructions are on pg186 in the price book.
ii. The MI-O Series has a connection outlet for the storage device and the
MI-O-HU Series has a built an integral storage compartment.
d) Oil interceptors come with vent connections on the sides. Local codes and
guidelines determined if the vents are needed. Unused vent connections can
be capped with a plug.
e) Oil interceptors come standard with a sediment bucket.
f) Oil interceptors are designed to function properly with a specified amount of
flow.
i. Sizing guidelines are on page pg186 in the Price Book.
g) MI-OS Series
i. Oil and sediment interceptor with “Special Duty” grates and sediment
bucket.
h) MI-SO Series
i. Similar design as the MI-O Series
ii. They include a draw-off valve, vent connections, and sediment bucket.
iii. Capacity is based on the interceptor’s holding capacity.
1. Required capacity is determined by maximum flow entering the
interceptor and the time required for the particles to settle.
E. Solid and Sediment interceptors
a) MI-HAIR Series
i. Installed under a sink designed to catch hair.
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ii.
Removable cap on the bottom allows access to the sediment bucket for
maintenance.
b) MI-SOLID Series
i. MI-SOLID-S is a cast iron body with an internal sediment bucket and
cleanout plug.
ii. MI-SOLID-LB a suspended interceptor that has access to the sediment
bucket from the bottom.
iii. MI-SOLID-M, -L interceptors have an internal sediment bucket. They have
the inlet lower than the outlet. This allows the sediment to settle at the
bottom of the interceptor.
iv. MI-SOLID-SA
1. Side access interceptor with a removable tray for cleaning.
2. The removable tray is perforated and designed to retain sediment.
v. MI-SOLID-TA
1. Top access with a removable sediment bucket and a perforated
screen located on the inside of the interceptor at the outlet.
2. Flow rates are given to match up with a standard MI-G Series grease
interceptor.
c) MI-SAND Series
i. Unit has internal baffles to help separate the sand and it includes two
sediment buckets.
ii. The capacity needed for sand interceptors is determined by the
maximum flow rate and the settling time of the sand entering the
interceptor.
d) MI-SD Series
i. Similar to the MI-OS Series but comes with fabricated grates that are
Light Duty” load rated.
F. Specialized interceptors
a) MI-FISH, MI-LINT, MI-RICE Series
i. All have two sets of internal perforated baffles to catch and retain the
corresponding sediment.
ii. The MI-FISH is the only model that has a sediment bucket.
G. Electronic Interceptors
a) MI-E-G, MI-E-O, and MI-E-O-HU Series
i. Same as the standard units with the electronic components.
ii. Each unit comes with a shut off valve on the inlet, float switch, and
control box.
1. The float switch monitors the grease or oil levels in the interceptor.
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2. The float switch turns on an alarm on the control box and closes the
shut off valve when the grease or oil reaches a certain level.
3. This stops any flow into the interceptor until it is maintenance.
4. The float switch is reset after maintenance and the shut off valve
reopens to allow standard operation.
H. Bolt On Extensions
a) A quick way to add length to the “C” dimension of a standard interceptor.
b) Used when the vertical adjustment of the interceptor is necessary to meet
the drainage piping elevation.
c) The lids are removed from the interceptor and the bolt on extension is
installed. The lids are then placed on the extension.
d) Extensions 6” and shorter come with longer bolts to mount the extension
and lid to the interceptor.
e) Extensions over 6” tall come with cross bars installed in the extension to
mount the extension to the interceptor and mount the lids to the extension.
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