Schier GB-75-B User manual

Part #: 4045-042-01
Find these instructions online at: schierproducts.com/gb-75-b
Contents
Special Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
Getting to Know the GB-75-B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10
INSTALLATION GUIDE
913-951-3300 | schierproducts.com
© Copyright 2020 Schier Products Company, 09/14/2020
GB-75-B 50 GPM 99% Efficient Great Basin™Indoor/Outdoor
Grease Interceptor

Schier | GB-75-B Installation Guide
page 2 of 10
SPECIAL PRECAUTIONS
Do not install this unit in any manner
except as described in these instructions.
Doing so may result in property damage, personal injury or death.
DO NOT AIR TEST UNIT OR RISER SYSTEM!
For Schier Grease Interceptor Installations - Failure to follow this guidance
voids your warranty
Provide at least 16"
clearance above unit for
routine maintenance.
16" min.
Install interceptor as close as possible
to fixtures being served
Installation Instructions
Installation instructions and additional
components are included with the
interceptor. Read all instructions prior to
installation. This interceptor is intended
to be installed by a licensed plumber in
conformance with all local codes.
Suspended Installations
Design trapeze to support the wet
weight of the unit. Do not partially
support unit or suspend unit using
metal U-channel to create a trapeze.
concrete floor
Support Inlet and Outlet Piping
For above grade installations ensure
heavy inlet and outlet piping (such as
cast iron or long runs) is properly
supported or suspended during the
entire installation process to prevent
connection failure or damage to
bulkhead fittings.
pipe supports
ODOR ALERT!
Interceptor is not a
sewer gas trap.
All upstream fixtures
must be trapped
ODOR ALERT!
Do not install air
gap on outlet side
of interceptor.
DO NOT USE CAST IRON
COVERS IN ABOVE GRADE OR
INDOOR INSTALLATIONS
Use composite cover C24H2 for
above grade installations
Fully Support Base of Unit
Install unit on solid, level surface in
contact with the entire footprint of
unit base
High Temperature Kitchen Water
If water is entering the interceptor at excessive temperature (over 150º
F), a drain water tempering valve (DTV) and approved backflow
prevention assembly must be installed. Most state and local plumbing
codes prohibit water above 150º F being discharged into the sanitary
sewer. Water above 150º F will weaken or deform PVC Schedule 40
pipe, poly drainage fixtures like interceptors and erode the coating of
cast iron (leading to eventual failure).

page 3 of 10
Schier | GB-75-B Installation Guide
SPECIAL PRECAUTIONS
For Schier Grease Interceptor Installations - Failure to follow this guidance
voids your warranty
Below Grade Installation Slab Requirements
A concrete slab to finished grade with rebar is required when installing
interceptor below grade.
Pedestrian Traffic or
Greenspace Areas Vehicular Traffic Areas
4" min.
slab 8" min.
slab
Hydrostatic/
Pressure Slabs
When installed under a
hydrostatic slab (slab
designed to withstand
upward lift, usually caused
by hydrostatic pressure)
interceptor must be
enclosed in a watertight
concrete vault.
concrete slab subject to hydrostatic pressure
watertight
concrete
vault
High Water Table
Installations
Interceptors and risers are not
designed to withstand water table
height in excess of the top of the
unit when buried (see figure). If it is
possible for this to occur, install the
interceptor and risers in a
water-tight concrete vault or
backfill with concrete or flowable fill
(wet concrete and flowable backfill
should be poured in stages to
avoid crushing the interceptor). At
risk areas include but are not limited to tidal surge areas, floodplains
and areas that receive storm water. Great Basin™models that are direct
buried in high water table scenarios must be installed with an anchor kit.
Model GB-75 uses model AK1 anchor kit.
DO NOT
COMPACT BACKFILL
MECHANICALLY
Compact by
hand only
max water table height
for direct burial
model AK1
anchor kit
Secure Cover Adapters
Cover adapters must be secured
to base units in above grade
installations with increased head
pressure conditions. Use cover
adapter tie-down kit model ATD1.
RebarRebar
Max Water Level
Risers are not designed
to retain water
Installations with Risers
Corrugated Riser Pipe
Requirements
Riser adapter model CA2 must be
used when installing interceptors
using 24" diameter corrugated
pipe as a riser. This will adequately
embed the cover adapter in the
concrete slab, preventing
cover/cover adapture failure
under traffic rated loads.
CA2
3 FCR2 Risers Max
94"
94"
6 - 94"6 - 94"

GETTING TO KNOW THE GB-75-B
1. Pickable cast iron cover (standard)
2. Cover gasket
3. Safety Star® access restrictor
4. Safety Star® tether
5. Cover adapter
6. Cover adapter gasket assembly
with upper and lower stainless
steel band clamps
7. Inlet diffuser cover (white)
8. Inlet diffuser
9. Inlet diffuser retaining nut
10. 4" cleanout plug (x2)
11. Outlet bulkhead connection
(optional) 4" FPT (x2)
12. Bulkhead connection gasket
13. Bulkhead connection retaining nut
14. Inlet bulkhead connection 4" FPT
15. 4" plain end fitting (x2)
16. Composite cover bolts
and washers (x4)
17. Bolted composite cover (optional)
18. Air relief/visual access
19. Outlet diffuser retaining nut
20. Outlet diffuser
21. Outlet diffuser foot retaining nut
22. Outlet diffuser (foot)
23. Outlet bulkhead connection
(standard) 4" FPT
24. 7/16" nut driver bit
25. Diverter plate retaining nut (for use
when outlet diffuser is repositioned
to an optional side outlet)
1 16
17
18
19
20
21
25
22
13
12
11
10
2
3
5
6
10
11
12
13
9
8
13
12
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24
4
13
15
12
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Schier | GB-75-B Installation Guide
page 4 of 10
7
Inlet diffuser
cover (white)

page 5 of 10
Schier | GB-75-B Installation Guide
1Test tank for water tightness
1a 1b
1c
Have a Leak?
Call customer care at 913-951-3300
Hours 8am-5pm CST, M-F
Cap all connection points with 4" cleanout
plugs using pipe thread sealant or tape
approved for use with plastics.
Remove cover. For base unit testing fill with water to
just above the highest connection.
Inspect unit, connections and gaskets for leaks. Check
water level at specific time intervals per local code.
Fill Line
Excavate hole at least 12" larger than interceptor on all sides and 6" deeper than tank bottom. Lay a level bed of
well-packed, crushed aggregate (approximately 3/4" size rock or sand, with no fines) in the base of hole.
12" 12"
6" 6" or more
2 Excavate Burial Pit

Schier | GB-75-B Installation Guide
page 6 of 10
3 Set Up Outlet Diffuser and Install Cleanout Plugs
3a Choose outlet location.
Screw in provided 4" cleanout plugs using pipe thread
sealant or tape approved for use with plastics. Do not cap
the inlet or outlet connections attached to the diffusers.
3c Cap unused connections(all configurations)
Side Outlet:
Go to Step 3b.
Straight
Through:
Go to Step 3c.
3b Reposition outlet diffuser (side outlets only)
Remove Safety Star® insert, leave tethered to unit. Unscrew diffuser retaining nut and
remove outlet diffuser. Do not remove the diverter plate found on the straight-through
bulkhead connection. Unscrew diffuser foot retaining nut and remove outlet diffuser foot.
Rotate diffuser toward chosen outlet, replace foot ensuring it will point to the back wall of
the unit and hand tighten foot retaining nut. Insert diffuser into chosen outlet and hand
tighten diffuser retaining nut. The diverter plate must now be secured to the
straight-through bulkhead connection using the extra retaining nut supplied with this unit.

This unit is supplied with a white inlet diffuser
cover to prevent the unit from swamping in
high flow/ increased head pressure conditions.
• If dimension "A" is 13 feet or less, the inlet
diffuser cover is not needed, go to Step 5,
Connect Piping.
• If dimension "A" is more than 13 feet, or a high
flow/increased head pressure condition exists,
follow Steps below.
4 Install Inlet Diffuser Components
Remove Safety Star® insert and remove inlet diffuser cover from the parts bag. Slide inlet
diffuser cover into top of inlet diffuser and rotate clockwise until cartridge drops onto the inlet
diffuser cover retainer pins. Continue rotating clockwise until pins are fully seated.
4a Install inlet diffuser cover
page 7 of 10
Schier | GB-75-B Installation Guide
For easy inlet diffuser cover
removal in deep burial
installations, 1-1/2" PVC SCH. 40
pipe may used as an extension
handle. Before risers have been
installed, cut pipe to length
and attach to top of cover
using PVC primer/cement.
Extension handle length should
be about 12" shorter than total
riser height.
4b OPTIONAL: install extension handle
Finished installation
showing optional
extension handle
inlet diffuser cover
retainer pin
cartridge
receiver slot

Schier | GB-75-B Installation Guide
page 8 of 10
5a Install plain end fittings
5b Connect interceptor to drain lines
5 Connect Piping
4" Plain End
Screw plain end fittings (included) into bulkhead fittings using pipe thread sealant or tape
approved for use with plastics. 6" connection types come pre-installed from the factory.
Place unit into final position and set level. Mechanically couple inlet and outlet drainage lines to
unit. Do not solvent weld. Ensure all upstream fixtures are trapped. Vent per local code. Installation
of 2-way cleanout tees to grade (by others) is recommended for buried installations.
Outlet
2-way
cleanout tee
Inlet
BURIED INSTALLATION
Kitchen floor
Add this vent if unit is installed
one or more floors below the
fixtures being served
Vent per local code
FLOOR BELOW INSTALLATION
COUPLING DETAIL
Drain
line
Flexible coupling
Plain end fitting
Bulkhead fitting
4" FPT4" FPT

6 Wet or Air Test Piping Per Local Code
Doing so may result in property damage, personal injury or death.
DO NOT AIR TEST UNIT OR RISER SYSTEM! Have a Leak? Call customer
care at 913-951-3300
Hours 8am-5pm CST, M-F
page 9 of 10
Schier | GB-75-B Installation Guide
7 Bring Covers Flush-to-Grade
The GB-75-B is ready for burial depth of 40" from finished grade to bottom of tank (or 13-1/2" to centerline of inlet).
Deeper burials will require extending the cover adapters and possibly adding risers.
Measure dimension X to determine riser height needed.
7a
See instructions included with FCR2.
Riser Height Risers
Needed Required
0" - 4" None (use adapter)
>4" - 34" FCR2 (x1)
>34" - 64" FCR2 (x2)
>64" - 94" FCR2 (x3)
Loosen the cover adapter upper band
clamp using 7/16" nut driver bit. Adjust
cover adapter heights as needed.
Maintain a minimum 2-1/2" insertion
depth. Tighten upper band clamp to 5
-8 ft. lbs. of torque using 7/16" nut driver
Bit. If required, cover adapters may now
be tilted up to 10º in any direction using
gasket flexibility.
7c Make final cover adapter adjustments
7b Install risers if required
COVER ADAPTER ADJUSTMENT DETAIL
2-1
/
2" minimum
Cover
Safety Star
access restrictor
Cover adapter
Gasket
Upper band clamp
Lower band clamp
Interceptor accessway

DO NOT COMPACT BACKFILL
Schier | GB-75-B Installation Guide
page 10 of 10
8 Install Anti-Flotation Anchor Kit
9 Backfill and Finished Grade
Fill unit with water for stabilization and float-out prevention. Backfill evenly around tank using crushed aggregate
(approximately 3/4" size rock or sand with no fines)or flowable fill. Do not compact backfill around unit.
9a Backfill
If the installation location is in a
high water table or at risk area
(including but not limited to tidal
surge areas, floodplains and areas
that receive storm water) the
GB-75-B must be installed with
Schier model AK1 anchor kit.
Max water table height for direct burial
Model AK1 anchor kit
Vehicular Traffic Areas:
Minimum 8" thick concrete slab with rebar required. Thickness of concrete around covers to be
determined by specifying engineer. If traffic loading is required the concrete slab dimensions
shown are for guideline purposes only. Concrete to be 28 day compressive strength to 4,000 PSI.
Use No. 4 rebar (ø 1/2") grade 60 steel per ASTM A615: connected with tie wire. Rebar to be 2-1/2"
from edge of concrete and spaced in a 12" grid with 4" spacing around access openings.
Pedestrian Traffic or Greenspace Areas:
Minimum 4" thick concrete slab with rebar required.
TOP VIEW 18"
min
45º
18"
min
18"
min
18"
min
Concrete slab
Rebar
9b Pour concrete slab to finished grade
Rebar