Question:

I have a 1,500-gallon tank with a 230 cfm free air, and 200 cfm at 15 inches Hg pump; I want to upgrade to something faster. On hard pulls, the pump gets hot and slow. I understand that more cfm just gets you to maximum vacuum quicker. So would it be better to go to a 300 cfm at 15 inches Hg pump and give it more air to keep it cooler, or go to a water-cooled pump at 230 cfm at 24 inches Hg? My 15-inch Hg pump does it now, but you have to fight it. I know that 300-350 cfm at 24-inches Hg would do it, but that would be like driving a nail with a 8-pound sledge hammer. I would like to hear from professional pumpers.

 

Answers:

We have a 2,500-gallon Progress tank with an air-cooled 350-cfm Masport pump. It works OK. On long pulls or steep pulls, you have to make sure to get some air in with the septage or you will be there all day. If we did it again, we would go with a larger cfm pump and most likely water-cooled.

 

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We purchased a truck about a year ago with 3,600-gallon tank and a Jurop 420. It’s a great pump, has 425-cfm and is liquid-cooled.

 

Small Tank and Pump Losing Suction

Question:

I have a Masport M2 connected to a 150-gallon waste tank for our very small pump truck. But it doesn’t produce anywhere near the sucking power of the other pump trucks. Symptoms are that it doesn’t hold vacuum, there is a hiss sound after the pump is stopped and there is a lack of vacuum. We can put our gloved hand over the suck hose and it is easy to remove. We have a 20-foot hose on the end, if that helps solve this mystery. I replaced all the pump vanes, cleaned out the unit and put it back in. Should there be any seals on the end plate?

 

Answers:

I don’t have much experience with those little tanks but the hissing, as you probably know, is caused by a leak somewhere. I would imagine seals are needed on the end plates. Metal to metal isn’t the best seal for vacuum.

 

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Could the hissing be coming from your vacuum relief valve being set too low or malfunctioning?

 

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It could be a check valve stuck open, a leak, and a dirty pump.