Precision Meters: Installation Instructions for flange type meters

Installation Instructions for flange type meters:

• Thoroughly flush the service line upstream of the meter to remove dirt and debris.
• If necessary thoroughly clean the flange faces by brushing with a wire brush.
• Set the meter in the line. Arrows on the side of the meter and above the outlet spud indicate the direction of flow.
• Install the meter in a horizontal plane, with the register upright, in a location accessible for reading, service and inspection.
• Insert the bolts with their heads on the meter side. i.e. With their threads pointing outwards.
• Place the flange gasket between the bolts and offer up the opposite flange carefully so that the gasket is central.
• Holding the bolt heads, fit each nut, beginning with the top most, only tightening by hand, ensuring that the flange gasket id captured in its correct position.
• When all nuts have been hand tightened and a final check is done to ensure that the flange gasket is correctly placed, proceed to tighten further – see bolt tightening guidelines below – using correctly sized spanners, preferable ring, one on the bolt head and the other for the nut.
• Once the tightening of the UP stream flanges have been completed, repeat the above for the DOWN stream flange.
• Test as below.

NOTE: To protect the meter flanges store the meter with flange protectors in place.

Bolt Tightening:

• Install all the bolts and nuts finger-tight, ensuring at all times that the flanges are aligned parallel to one another.
• Tighten the bolts in a crisscross sequence as shown in Fig. 4, using a torque wrench with 20% of the final torque appropriate to the bolts used.
• In the four remaining steps, repeat step two four times, each time increasing the torque by 20% of the final value, always using the crisscross pattern.
• After reaching the final torque, use rotational tightening until all bolts are stable at the final torque value (in general two complete times around is required).

Gasket Installation:

NOTE: The importance of proper gasket installation cannot be stressed enough.

Basic explanation of how to properly bring the flanges together in parallel and in stages once the gasket is in place and then to properly compress the gasket.
DO NOT REUSE old gasket, or use MULTIPLE gaskets.
• Ensure that the flanges are in good condition.
• Visually examine and clean flanges, bolts, nuts and washers.
• Ensure that NO anti-seize has been used on any gasket contact surface.
• Never use any sheet gasket material.
• Replace components if necessary.
LUBRICATE the bolts, nuts and nut bearing surfaces.
• Install the new gasket, bolts and nuts.
• Be sure gasket is properly centred.
• Check gap for uniformity.
• Number bolts in cross-pattern sequence according to the appropriate sketch (see Fig 1 & 2).
• Starting at the bolt No 1, use the appropriate cross-pattern tightening sequence in the sketch (Fig 3 & 4) below for Rounds 1, 2, and 3 and/or Round 4 (each sequence constitutes a “Round”).
• It is imperative to apply the correct torque value, of the bolts being used, to get the proper gasket compression.
• As a minimum, four passes are required.

NOTE: As a general rule, soft gaskets are intended for service in Class 300 and below. For applications above Class 300 consult your supplier representative.

4-bolt and 8-bolt flanges:

• Round 1 – Tighten to 25% of- final torque.
• Round 2 – Tighten to 50% of final torque.
• Round 3 – Tighten to 100% of final torque.

Fig 1

Fig 2

12-bolt flanges and above:

• ROUND 1 – Tighten to 20% of final torque.
• ROUND 2 – Tighten to 40% of final torque.
• ROUND 3 – Tighten to 80% of final torque.
• ROUND 4 – Tighten to 100% of final torque
• Check gap around the circumference between each of these ROUNDS, measured at every other bolt. If the gap is not reasonably uniform around the circumference, make the appropriate adjustments by selective bolt tightening before proceeding.
• FINAL ROTATIONAL ROUND – 100% of Final Torque (same as Round 4 above).
• Use circular, clockwise tightening sequence, starting with Bolt No. 1, for one complete ROUND and continue until no further nut rotation occurs at 100% of the Final Torque value for any nut.
• FINAL – RE-TORQUE. After twenty-four hours repeat ROUND 3 or 4 (above) followed by a ROTATIONAL ROUND.
• Tests show that a large percentage of the short-term bolt pre-load loss occurs within twenty-four hours after initial tightening. The FINAL, RE-TORQUE ROUND, recovers this loss. This is especially IMPORTANT for PTFE gaskets.

Torque Values:

• Bolt specifications determine the maximum torque to which they should be tightened to.
• Use reference Bolt Torque tables available from Engineering Hand Books or the Bolt supplier to determine the correct ratings for the bolts being used.
• Do not exceed these values EVER as the bolt, when over tightened, is then useless.
• Over tightening will also lead to distorting the flange/s and allow leaks to develop.
• Any lubrication used on the nuts or faces behind the nut will need to be taken into consideration when calculating the correct torque to be applied.

To test the installation for leaks:

A. Installation test with ONLY an upstream shutoff valve:
• Open shutoff valve slowly, to remove air from the meter and service line.
• Open a downstream tap slowly to allow entrapped air to escape.
• Close the downstream tap.

B. Installation test with BOTH an upstream and downstream shutoff valves:
• Close the downstream shutoff valve.
• Open the inlet shutoff slowly until meter is full of water.
• Open the outlet valve slowly until all air flushes out of meter and service line.
• Open a downstream tap slowly to allow entrapped air in the downstream pipe to escape.
• Close the downstream tap.

Precision Meters: Installation Instructions for flange type meters

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