Humidity Indicator Plugs – FAQs


Can I get custom humidity indicator plugs?

Yes. AGM’s Engineering Department has designed hundreds of modified and custom versions for previous customers.

What does the thread callout mean (3/4-14 straight pipe IAW PPP-P-420, Class D)? Do I need a 3/4” hole in my container to mount this device (TA356, TA350, TA354 and similar items)?

This thread is misleading because it actually has a maximum major diameter of 1.027”. Therefore, the recommended mounting hole diameter is 1.050″ (26.7 mm). This thread is commonly used on the small bung of a 55 gallon drum. The reason our humidity indicators have this thread is that they were initially used most commonly on 55 gallon drums.

What pressure will these plugs withstand?

All of AGM’s plug designs will withstand 10 psig in either direction while our TA284 series is guaranteed to 500 psig outward for high pressure applications.

What is the tightening torque I should use when installing my humidity indicator?

We recommend 30-40 in-lbs for all humidity indicators we offer that are made of metal except for the TA28X series, which utilize an NPT thread form. For the TA28X series, a higher torque might be required. For the TA380 series (made of SAN plastic), we recommend 5-8 in-lbs, or just finger tight.

How do I replace the humidity indicator card inside the plug and what wrench size is required?

Follow these simple steps:

  1. Hold housing by the 1.375” hex flange.
  2. Insert a 1/2” hex wrench (Allen wrench) into the lock screw & turn counter-clockwise to loosen.
  3. Remove lock screw.
  4. Remove Teflon washer.
  5. Remove old humidity indicator card.
  6. Install new humidity indicator card.
  7. Install Teflon washer.
  8. Install lock screw.
  9. Hold housing by the 1.375” hex flange & torque lock screw to 50+/-5 inch-pounds.