Meriam 70H_72H High Pressure Wet Tap Accutubes with Integral 3-Valve Head and Optional RTD - Manual (Page 21)

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4.7.4.2 Lightly snug down the packing gland socket head cap screws just
enough to set the packing in place and remove any clearances. Turn the
hex socket head cap screws an additional 1-1/2 turns to pre-load the
packing rings. Turn the screws a small amount alternately so as to
tighten the assembly slowly and evenly from both sides.
4.7.4.3 Verify the instrument valves on the Accutube are closed.
4.7.4.4 Open the insertion valve. Verify all joints and packing is sealed tightly
as the entire assembly is now pressurized. The packing assembly can
be tightened further if required.
4.7.4.5 Remove locking rod from crank handle.
4.7.4.6 Insert the probe into the pipe by turning the crank handle counter
clockwise to pull the Accutube into the line. Use this procedure until
the probe touches the opposite side of the pipe.
4.7.4.7 Withdraw the probe from the opposite side of the pipe wall 1/8”. This
clearance is a provision for thermal expansion and assures centering of
port holes.
4.7.4.8 Position crank handle so ¼” threaded hole on lower insertion bar is
visible. Insert locking rod.
4.7.4.9 Again inspect the packing gland assembly for leakage. If required,
tighten the packing screws an additional amount.
4.7.4.10 The Accutube is now in working condition.
4.7.5 SPECIAL DOUBLE-SUPPORT WET-TAP MODEL 37L WITH SOCKET OR
GEAR DRIVE
4.7.5.1 Double support type sensors require a second hole through the opposite
side of the pipe. Location of this hole is critical as it establishes proper
alignment of the probe with respect to the flow. A common method of
locating the opposite support hole is by wrapping a piece of string
totally around the pipe, with the string crossing the center line of the
existing drilled hole at each end, and running square to pipe. The
position can be marked at 1/2 the total length of the string. This work
can only be done with no flow in the pipe. If the flow cannot be
stopped for installation, contact Meriam for special arrangements.
4.7.5.2 Verify that the operating pressure and temperature are within the
published limit of the Accutube, probe valves, and mounting assembly.
Refer to Table 5 for maximum values. The data sheet of the individual
Accutube lists the maximum insertion/retraction flow values. These
values should never be exceeded.