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Operating and maintenance instructions Section 4: Maintenance
3-9008-701 Rev J January 2015
Measurement Piston and Flow Tube 55
5. If the poppet valve has been removed from the measurement piston, install it at this
time. Torque the poppet bolts.
NOTE: For high temperature 2 piece poppets, the 3/8-24 screw requires 24 ft.lbs (33 N.m)
torque
6. Lubricate the two measurement piston seals with light oil and install them on the
piston. The open sides of the two seals will be facing away from each other when
installed correctly. Each seal will require proper fitting. Once the seal is around the
groove, the seal must be pushed into the groove. A ‘snap’ will be heard once the seal
seats in the groove. Be sure to check that the entire seal is properly seated.
7. Test fit of the rulon riders on the measurement piston. Trim any excess length so that
there will be a 1/16” (2 mm) gap between the ends of each rider. Remove the riders
from the piston and lay them over the end of the flow tube.
Important:
The 12” Compact Prover has two different sized riders; a thick rider and a thin rider. The thick
rider fits in the upstream groove of the piston. The thin rider fits in the downstream groove of
the piston, between the two piston seals. All other size provers have identical riders.
8. Lubricate the inside of the flow tube with light oil. Align the measurement piston with
the flow tube and insert the actuator shaft into the guide conduit. Pay attention to the
threaded mounting boss (for the detector shaft) and align as necessary.
9. Carefully insert the measurement piston into the flow tube until the first rulon rider
groove is about to go into the flow tube. Install the first rulon rider onto the
measurement piston with the gap at the bottom of the piston. Lubricate the rider with
light oil.
Table 4-1 Torque table
Prover size Poppet bolt size
Torque requirement
ft - lbs N - m
8
1/4 - 20
6
8
12m
3/8 - 16
15
20
12
3/8 - 16
15
20
18
3/8 - 16
15
20
24
1/4 - 20
6
8
1/2 - 20
25
34
34
3/8 - 16
15
20
40
1/2 - 13
25
34