Calibration & Repairs to Stay on Schedule

The term cold loop and hot loop are names sometimes used during calibrating. A cold loop can be interpreted as a continuity check from point to point, meaning no power voltage or amperage are applied to the circuit. A hot loop, which is only done after a cold loop is complete, is much more involved. The instruments, such as a valve, are tested to operate across its functional range. Digital or discrete is checked that it opens and closes correctly when commanded from the front end and then verified in the field and on the equipment graphics. Analog is usually tested in increments of 25, 50, 75 and 100%, then fully closed again and tested from the front end and verified in the field.

MSC was tasked with assisting with calibration of BAS instruments and various control valves across multiple systems. However, after the cold loop testing or point to point was completed it was during the hot loop testing where unexpected problems began. Positioners on valves were not functioning or damaged during installation. E to Ps we’re also found to be troublesome having no repeatability and several needed to be ordered right away. Pneumatic fittings were leaking on several valves, and in one or two cases the wrong springs were installed in the actuators. There was little that could be done beforehand as these were unexpected calibration issues. The good news is the valves had universal positioners and E to Ps and could be ordered, delivered and shipped overnight once located.

After the new parts were received and installed, MSC and the commissioning agent went back to the valves in question and worked early mornings before the day began to complete the loop check so system commissioning could still be completed on time. Valve part failures were reasonably easy to identify during loop check. Locating the distributor, finding the location of parts and drop shipping them from the manufacturer were the challenge and took a few days to accomplish.

Schedule-wise it took some time to identify the parts problems, find the local representative, order parts, install them and retest thus taking a week off of some system commissioning schedules. However, organizing system parts delivery and working early mornings as parts came in provided the commissioning team the opportunity to stay on schedule during the project!

About MSC - The Go To Guys

We are a service sub-specialist in the technical intricacies of HVAC, process cooling, and building automation systems in commercial, industrial, and institutional environments. MSC is recognized as the leading industry expert in solving elusive problems and attaining peak performance from clients & mechanical equipment and overall systems.

Located in northern New Jersey, MSC is the only specialized contractor of our kind in the Northeast and Mid-Atlantic regions. We are MSCA STAR-qualified, NEBB-certified, fully-licensed in electrical, plumbing and HVAC, and our engineers and technicians are the most knowledgeable in our field.

MSC - Mechanical Service Corp.
41 South Jefferson Road
Whippany, NJ 07981
973-884-5000
http://www.mscnj.com