Hawkeye Marsh Hawk User Manual
► 3/4 in. Box / Socket Wrench
► 1/2 in. Box / Socket Wrench
► 9/64 in. Allen Wrench
This document contains the recommended procedures installing and maintaining a Hawkeye Marshhawk Thief Hatch.
Requirements
The Marshhawk has a standard 8” API flange connection, and re-
quires a SCH 40 or lighter nozzle. Other mounting options, such
as ANSI flange or other API connections are accommodated with
adaptor spools and risers. Consult the vapor control section of our
website, or call us for more information.
Tools
Parts Required
A.) Installing the Marshhawk Thief Hatch
Place Tank Gasket on the 8” API Tank Flange
and align holes.
Installation & Maintenance Guide
Marshhawk Thief Hatch
QTY Part
Installation
► 1 Marshhawk Thief Hatch
► 1 8” API Tank Gasket
► 16 1/2 UNC x 1-3/4 Bolts & Nuts
► varies 2 ozsi and 1 ozsi Pressure Spacers as required.
Maintenance
► 1 Replacement Pressure / Vacuum Gasket
► Dow Corning #4 Electrical Insul. Compound (or eq.)
1.)
Fasten with the supplied 1/2 UNC Bolts and
Nuts with a 3/4 Box or Socket Wrench
3.)
Mount Marshhawk on base gasket and align
holes.
2.)
Remove the spider cage assembly by pressing
down on spring retainer and rotating counter
clockwise to disengage from J-slot. Lift spider-
cage assembly straight out of the hatch body.
G
1.)
Use spring retainer to compress the spring.
Remove the retainer screw and washer with
the 1/2 wrench, and remove the spring retainer.
2.)
Add or remove pressure spacers to increase or
decrease activation pressure, respectively.
Each standard pressure spacer changes acti-
vation pressure by 2 ozsi. Follow directions in
reverse to reassemble the thief hatch.
Hawkeye recommends activation pressure 2 ozsi
below the tank’s pressure rating.
3.)
Marshhawk Installation Instructions, May 2010
1
Contents
A.) Installing the Marshhawk Thief Hatch
A1.) Hatch Installation
A2.) Pressure Spacer Adjustment
B.) Maintaining the Marshhawk Thief Hatch
B1.) Replacing Pressure / Vacuum Gasket
B2.) Relubrication
B3.) Antifreeze solutions
A1.) Hatch Installation
A2.) Pressure Spacer Adjustment
↑P ↓P
►►
►
►
SCH 40
or lighter
Hawkeye Industries Inc.
2
B.) Maintaining the Marshhawk Thief Hatch
B1.) Replacing the Pressure / Vacuum Gasket
B2.) Relubrication
B3.) Antifreeze Solutions
Remove the 12 #8-32 NC Socket Head Cap
screws with the 9/64 Allen wrench, freeing the
gasket retaining ring.
Using light pressure, push the vacuum plate
out of the way, and slide the gasket around it,
and off of the spider cage.
Generally, the more active the vent action of the hatch, the more frequent
relubrication should be performed. Specific relubrication requirements are
application specific, and are determined by the following variables:
► Chemical exposure
► Elevated pressure
► High flow velocity
► Elevated temperature
► Utilization (i.e. if hatch is primary relief)
Hawkeye factory-applies Dow Corning 4 Electrical Insulating Compound
to the vacuum and pressure gasket, and recommends the same com-
pound for any field relubrication.
►Excellent seal and release properties
►-57°C to 204°C
► Moisture Resistant
► 4.5% Bleed, 24 hr/200°C
► 1.4% Evaporation, 24 hr/200°C
► Non-toxic and odorless
It is not recommended to use any kind of antifreeze solution on a nor-
mally-operating Marshhawk thief hatch -- even as a preventative meas-
ure. However, if there is evidence of the hatch icing up, a compound with
suitable gasket compatibility is required. Please consult the supplied
chart and ensure that the solution used will not compromise the sealing
effectiveness of the Marshhawk Thief Hatch.
Align holes on new gasket with holes on spider
cage and retaining ring. With light an even
torque, replace the 12 #8-32 NC Socket Head
Cap Screws (I)
Remove the spider cage assembly from the hatch body as in Section A2, Step 1 before proceeding.
1.) 2.) 3.)
Hawkeye offers three gasket materials for the Marshhawk Thief Hatch:FKM
(Viton), FEPM (Aflas) and FFKM (Kalrez). Each with different properties,
temperature ranges and chemical compatibilities. Please ensure the se-
lected gasket materials suitable for your application prior to ordering a re-
placement. Call us for assistance. The following operating temperature
range table is provided for information only.
-
Gasket Material
Antifreeze Solution FKM (Viton) FEPM (AFLAS) FFKM (Kalrez)
Methanol
4 11
Ethanol
311
Isopropanol
111
Ethylene Glycol
111
1 - Satisfactory 2 - Fair 3 - Doubtful 4 - Unsatisfactory
►►
50 0 50 100 150 200 250 300 350
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