Question:
I recently had one of my employees “smoke” a vacuum pump. He said he was just doing his job like he normally does — nothing different — and the pump simply started smoking. I told him a properly maintained pump won’t smoke under ordinary working conditions. He claims he did nothing wrong. Maybe he did or maybe he didn’t, but my question is fairly basic: What will cause a vacuum pump to get so hot that it smokes?
Henry Windham
Buffalo, N.Y.
Answer:
Nothing like “smoking” a pump to make smoke come out of the boss’s ears. There are three primary reasons why a pump will start smoking:
1. This is the answer everyone thinks is the only answer: There’s no oil in the pump. Every vacuum pump requires a steady flow of lubrication. Should the pump run out of oil, the rotor and the vanes, which are turning at around 1,100 rpm, will definitely create heat inside the pump. It won’t take long for the heat to turn the residue oil into smoke, and only a bit longer than that to permanently damage the pump. So, rule No. 1, fill up the oil reservoir on your vacuum pump every workday.
2. Your vacuum relief valve is set too high. This will depend on your elevation to some extent. If your vacuum relief is set too high, the pump will run for a longer period of time before the relief of the valve comes into play. The longer work cycle will again create heat in the pump and if allowed to continue — you get smoke. Consequently, rule No. 2, adjust your vacuum relief valve to the proper setting for your elevation.
3. This is a combination answer. That is to say, any one of these things could create problems and heat for your vacuum pump. One is very basic: The wrong oil was put into the pump. Every vacuum pump manufacturer recommends certain oils be used in their pumps. Other oils will not perform like the recommended oil, consequently heat is generated and here comes that smoke cloud. So use the right oil, consistently and constantly, in the pump. Don’t get in a hurry and substitute the stuff you have on the shelf because it happens to be there. Simply put, the oil you put into your car or truck isn’t the oil (in most cases) that you should be dumping into your vacuum pump.
Another possibility is that the pump is running too fast. Vacuum pumps are designed to run at certain rpms. The speed is different for each vacuum pump, depending on the manufacturer. The pump installer will usually set it to run within the specifications required by the manufacturer. Many pumps are designed to run around 1,100 rpm with a high range around 1,300-1,400 rpm. Some installers will use a smaller pump and set it at the higher range to get it to work as quickly as a larger pump. If the pump is set to run at a higher-than-recommended rpm, the smoke will begin to show.
As a side note, make sure your installer or the provider of the pump understands the size of the tank you are using. Remember, the size of pump on your truck should be based on the size of tank you are hauling. If you are using a small pump on a large tank, the extra time needed to evacuate the tank could cause the pump to overheat. Not only that, but a small pump on a large tank is going to have a short, sweet and possibly smoky life.
Add it up
When your employee says that nothing had changed from previous workdays, but the pump started smoking anyway, something is up. If everything was the same as the previous time, there would have been no smoke, the pumping would have been done and another successful day of work would have been accomplished. Somewhere between the last working day and the smoking day, something changed and it is most likely one of these reasons.
So before it happens again, find out what the employee did to create the change in the operation of the vacuum pump. Pumps are expensive. Make sure all your employees understand what is happening when a pump starts smoking. When it comes to the portable sanitation industry, there is nothing romantic about the phrase “Smoke gets in your eyes.”
