Small Business Owners Iron Out Tank Capacity and Vacuum Pump Issues

If you don’t want your truck to jump and chug as the ball inside the primary cuts off the air supply, don’t push your vacuum tank capacity to the limit.

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QUESTION: I’ve noticed that when my truck is close to being full, the ball in the primary jumps up prematurely and closes off my supply line when I still have room for about 75 to 100 more gallons. Yesterday I pumped 780 gallons and my truck should be able to hold about 825 gallons. The truck jumps a bit because of the free air entering the tank, and this must make the ball jump inside the primary, closing it off. Are there tips or tricks around this without modifying my primary? I have a low-profile 12-inch manway/primary combo.

ANSWER: There are some things you can do, but let’s back up and take a closer look at your process of pumping. First, remember the power of vacuum is incredibly strong. I have heard from many pumpers who use a common-sense rule. They call it the “10 percent rule.”

It’s simple. When you are 90 percent full, the potential for the primary closing off the system becomes very high. Pushing to your tank’s capacity of 825 gallons is pressing your luck. You have approximately 5 percent volume left in the tank, and the ball in the primary is already getting very close to jumping up to save the pump.

Another way of looking at it is to consider the amount of air left in the tank. If you have a round tank that is 95 percent full, the primary ball is almost riding on the liquid. When you hit the air at the bottom of the tank you are pumping, the ball has no choice but to jump up. I have seen other pumpers utilize a primary with two round balls and a sight glass. But you mentioned not wanting to change out the primary.

Think about it. Your primary ball is very close to sitting on the pumped waste. To do the math, on an 825-gallon tank, considering the diameter, the ball is simply too close to the top. Your options: Change out the primary, which really won’t solve the problem. Maybe it will give you a few more gallons before the primary closes up. Or, get a new truck with a larger tank capacity. For now, it is likely you’ll have to settle for the 780 gallons, or less, to be on the safe side.

You should get the pump you specify

QUESTION:  When I ordered a vacuum truck recently, I told the builder I wanted a certain brand of vacuum pump. All of my trucks have that pump and I did not want another brand. It is so much easier to do maintenance when all the pumps are the same. I can keep all the necessary parts and I can always have the right type of oil on hand.
When I picked up the truck, I noticed a different pump; the builder’s response was, “It’s a better pump than the one you’re using.” I told him I wanted the pump changed out and replaced with the one I ordered. After some heated conversation, I finally said, “It’s my brand of pump, or no sale.” Reluctantly, he agreed. Why do manufacturers get so locked in on parts and pumps?

ANSWER: Some tank manufacturers get a bigger discount on certain brands of pumps if they buy a certain amount of pumps in a year’s time. Like you, some manufacturers want to keep their inventory simple, so they use the same brand of pump on all their units. When you order a truck with a certain brand of pump, however, you should get exactly what you order. 
Some manufacturers provide a spec sheet listing everything you are purchasing. It will include the specific pump and parts you will be getting on your truck. Once a buyer is satisfied with the spec sheet, he signs off on it, and upon delivery he can check to make sure he is getting everything, including brands, that he ordered. This eliminates the problem you had with your manufacturer.

It’s usually easy to check the wear on your pump vanes

QUESTION: When I run my truck, the amount of vacuum seems to be less and less at each stop. Is there any way to check my vanes without removing the pump from the truck and making it a huge job removing, checking, replacing, etc?

ANSWER: Most pumps have a bolted plate that covers the interior of the pump. For these pumps, checking the vanes is relatively simple. When the truck is in your shop, simply remove the bolts and take away the cover. Now you can view the interior of the pump and check the vanes for wear. Over time, all vanes wear down. As a general rule, vanes should be checked at least once a year.


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