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Caps and Fasteners Torque Requirements
IMPORTANT
Only use Allen wrenches of sufficient hardness (50Rc −
Rockwell Harness Scale minimum). Fully insert the
wrench into the valve stem recess.
Service valve stems are factory−torqued (from 9 ft−lbs for
small valves, to 25 ft−lbs for large valves) to prevent
refrigerant loss during shipping and handling. Using an
Allen wrench rated at less than 50Rc risks rounding or
breaking off the wrench, or stripping the valve stem
recess.
See the Lennox Service and Application Notes
Corp.0807−L5
(C−08−1)
information.
When servicing or repairing HVAC equipment and
components, ensure the fasteners are appropriately
tightened. Table 1 list torque values for various caps and
fasteners.
Table 1. Torque Requirements
Parts
Recommended Torque
Service valve cap
8 ft.− lb.
Sheet metal screws
16 in.− lb.
Machine screws #10
28 in.− lb.
Compressor bolts
90 in.− lb.
Gauge port seal cap
8 ft.− lb.
506728−01
for
further
details
and
11 NM
2 NM
3 NM
10 NM
11 NM
Operating Gauge Set and Service Valves
IMPORTANT
To prevent stripping of the various caps used, the
appropriately sized wrench should be used and fitted
snugly over the cap before tightening.
OPERATING SERVICE VALVES
The liquid and vapor line service valves are used for
refrigerant recovery, flushing, leak testing, evacuating,
weighing in refrigerant and optimizing system charge.
Each valve is equipped with a service port which has a
factory−installed valve core. Figure 2 provides information
on how to access and operate both angle− and ball−type
service valves.
USING MANIFOLD GAUGE SET
When checking the system charge, only use a manifold
gauge set that features low−loss anti−blow back fittings.
Manifold gauge set used for HFC−410A refrigerant
systems must be capable of handling the higher system
operating pressures. The manifold gauges should be rated
for:
S
High side
Pressure range of 0 − 800 pound−force per
square inch gauge (psig)
S
Low side
Use with 30" vacuum to 250 psig with
dampened speed to 500 psig
S
Manifold gauge set hoses must be rated for use to 800
psig of pressure with a 4000 psig burst rating.
Page 4
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