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A. 2-1/8-inch Dia. Bellows (Cont.)
5. If the pointer is set above zero, rotate the spring adjustment clockwise
until the pointer is set at zero. If the pointer is below zero rotate the
spring adjustment conterclockwise until the pointer is set at zero.
6. Replace and tighten the lock nut. If the pointer shifts from zero, loosen
the lock nut and reset the pointer as in step 5. Tighten the lock nut.
7. Replace the low-pressure housing and install NEW bolts (new gaskets
are recommended). Use the torque values listed in Tables 4-2 through
4-4.
Refer to Housing Bolt WARNING, para. 4-5, page 19.
8. Calibrate in accordance with the manual for the actuated instrument.
B. 3-3/4-inch Dia. Bellows Without Kickoff Spring
(>50" w.c.)
1. Remove the instrument from service.
2. Remove the pressure housing bolts and the low-pressure housing.
3. With the pointer set at zero, remove the lock nut retainer nuts, and the
range spring assembly. To remove the range spring assembly, rotate
the assembly counterclockwise while pulling outward on the assembly.
NOTE: The pointer will shift from zero. This is a normal action and the
pointer should not be readjusted at this point.
4. Thread the new assembly onto the push rod, and align the holes in the
range spring assembly with the spring posts. Replace and tighten the
retainer nuts.
5. Using a spanner wrench, rotate the spring adjustment until the pointer
is set at exact zero. Replace and tighten the lock nut. The pointer must
remain at thezerosetting. If the pointer shifts from zero, loosen the lock
nut and repeat this step.
6. Replace the low-pressure housing and bolts (new gaskets are recom-
mended). Use the toque values listed in Tables 4-2 through 4-4.
Refer
to Housing Bolt WARNING, para. 4-5, page 19.
7. Calibrate in accordance with the manual for the actuated instrument.
C. 3-3/4-inch Dia. Bellows w/Kickoff* Spring
(see Figure 4-2)
NOTE: The kickoff spring is supplied with the 0-40" w.c. and lower range DPUs
as standard equipment. It is optional with 0-50" w.c. DPUs.
*Also referred to as the "anti-stick" spring.
Remove the instrument from service. Set the pointer (or pen) at zero, using
the instrument zero adjustment.
2. Remove the pressure housing bolts and remove the low-pressure housing.
3. With the pointer set at zero, remove the lock nut, four spring retainer nuts,
washer and lock nut, and range spring assembly.
NOTE: The pointer will shift from zero. This is a normal action and the
pointer should not be readjusted at this time.
4. Install the range spring assembly, using a 1/2-inch open-ended wrench to
connect the push rod to the low-pressure bellows cup.
NOTE: The range spring assembly consists of the range springs, kickoff
spring assembly, and the push rod. The assembly is furnished as a complete
and assembled unit.
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