Airlock with a slack chain interrupted by cleaning pulses

When we did a periodic test on a baghouse dust collection system, an abnormal noise from the airlock got our attention. The baghouse is equipped with a low-pressure, high-volume pulse cleaning mechanism.

After carefully studying, we found that the airlock’s rotation was interrupted each time the cleaning pulse was released, and consequently the airlock made noise.

We took off the chain cover, and a slack chain came into view (Figure 1 & 2). Apparently, the shaft of the gearbox reducer moved gradually closer to the airlock body shaft after years of operation because the mounting bolts of the reducer were not tight enough originally.

Because the airlock is a slow running device, we adjusted the gear reducer position and set the slack of the chain to 5% of the center to center distance of the shafts. After this was done, the airlock went back to normal.

Figure 1 Slack chain on the airlock, image 1

Figure 2 slack chain on the airlock, image 2

For comparison, Figures 3 and 4 were taken just one year ago in the last periodic test of the system. The chain was a little slack too, but the airlock ran normally without any noise.

Figure 3 airlock chain one year ago, image 1

Figure 4 airlock slack chain one year ago, image 2

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