ONICON System-10 BTU - Manual (Page 11)

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System-10 BTU Meter Manual 03/15 - 0651-16 / 18323 Page 11
3.2.2 Thermowell Installation
IMPORTANT NOTE
It is important that no dirt or other foreign material be allowed into the thermowells as this could
affect the thermal response of the system.
i
3.2.2.1 Standard Thermowells
Standard thermowells are for new construction or scheduled shutdown. The most
common installation methods are shown below. Refer to Appendix A-6 for
thermal insulator installations and Appendix A-7 for high temperature (>300° F)
thermowell installations. Consult ONICON for special applications.
NOTES: 1. Thermowell length varies with pipe size.
2. Use no additional bushings to ensure that tip of thermowell is inserted into flow stream.
3.2.2.2 Hot Tap Thermowells
Hot tap thermowells are designed for retrofit applications where it is not practical to
isolate and drain the pipe section prior to installation. The thermowell is installed
through a 1” full port ball valve as shown in the drawing below. A wet tap drilling
machine equipped with a 7/8” drill is required to perform this type of installation.
Install the valve assembly as shown in the drawing and then drill the 7/8” hole
using the wet tap drilling machine. Once the valve assembly has been installed
and the hole has been drilled, the thermowell can be inserted into the flow stream
without a system shutdown.
!
WARNING
SYSTEM MAY BE UNDER HIGH PRESSURE. Be sure to hold the conduit box firmly by hand before
slowly loosening the position clamping nut when installing, adjusting or removing the thermowell.
Failure to do this will allow the pressure to suddenly and rapidly force the thermowell from the
pipe, potentially causing serious injury. The thermowell could also be damaged or break apart
causing a break in the water seal with the resultant loss of large amounts of water.