QUESTION:
I have a fairly basic question: How many places in a vacuum system can get screwed up or plugged? When I go looking to find out what’s wrong with my truck, how many different places are there to look?
Troy Delmonica
Los Angeles, Calif.
ANSWER:
There are several points in the vacuum system of a portable sanitation service truck that can “plug up” the operation. Knowing these points will make it easier for the operator to find the problem, fix it, and get back on the path to profit. Let’s take a typical system and work our way through it:
1. You’re pumping just fine when suddenly nothing is being sucked up into your wand. First, look at the end of the wand. If there is no vacuum pulling anything into the system, you may have pulled a large rag or something similar into the end of the wand. If there is no rag there, then there are such things (and, yes, we’ve seen them and people have actually paid us to find them) as tennis balls that zip into the line and then get stuck in the hose. To check your theory, turn off the pump, disconnect the hose and see if there is vacuum at the valve leading into the tank. If you have vacuum at the valve, find the “plugger,” remove it, connect the hose and begin working again.
2. If you find the rate of vacuum has decreased and there is no obstruction in the hose, check to make sure the vacuum tank isn’t already full. I know it sounds obvious, but this is another thing we’ve seen over the years. It’s weird telling a PRO the unit will not pump well because there’s no room to put anything. But it happens.
3. The next point involves the primary shutoff on the top of the tank. If the vacuum is bogging down, open the primary and check its condition. You also will find how full your tank is. It happens at times that the float ball in the primary gets sucked up into the air path and sticks in that spot. With the float ball blocking the airflow, vacuum will definitely decrease. Check the primary to make sure the cage and ball are in good condition.
4. The hose between the primary and the secondary should be checked from time to time, especially if there has been a problem with the secondary, which we will discuss in a moment.
5. If you ever forget to empty your secondary at the end of a pumping day, you will end up with problems the very next day. Some of the waste that sat all night will slide up into the hose and into the pump. That will hinder pump efficiency. As mentioned, the secondary should be emptied and cleaned every day. It is the last line of defense to protect the pump. Allowing waste to build up in the secondary will lead to problems.
6. Reduced vacuum could indicate the vanes inside the pump are wearing down. It might also be the bearings are wearing out on the rotor. The pump can be easily opened up and a rebuilding kit from the appropriate pump supplier can be installed. Rebuild kits usually include gaskets, bearings and vanes.
7. Depending on how your pump receives oil — automatic oiler or an assisted-tank type oiler — make sure the pump has oil. Yes, we’ve even seen people who run out of oil and wonder what happened to their pump. (The smoke from the generated heat coming from the pump should have been a clue!).
