When a vacuum truck is operated, air will circulate within the vehicle and create a vacuum effect inside the tank. Basically, the vacuum effect is created by engaging a pump to generate air flow in and out of the tank. To protect the machine from being damaged, there are components vital for safety such as a mesh filter that inhibits foreign materials from entering into the pump and shut-off that protects the tank from overfilling. Another component that plays a crucial role in operating a vac truck for sale is the relief valve which decreases excess pressure to prevent tank collapse.
Types of Controllers
- Air-Operated – This version is activated through a switch on the master control panel. The master switch must be turned on so the vacuum switch will function as expected. During installation, if the setting has been established prior to purchase, it will be put at the default setting of 100 psi. In addition, the controller can be used with or without petroleum-based oil lubrication.
- Manual – This model on a vac truck for sale is located near the master control panel and is used if the automatic relief valve fails to properly function. It can be opened by turning the handle and ensuring that it is in line with the valve; it can be turned off by squeezing the trigger level handle and putting it perpendicular. This can be adjusted to necessary vacuum pressure and provides total control to the user.
- Automatic – This is a hydraulically-operated controller for sustaining pressure, varying from no-flow to full-flow without any system problems. When the pump discharge pressure goes beyond the set limit, it permits a back flow to the pump.
Inspecting and Testing
To ensure safety and prevent damage to life and property, there are certain measures that should be followed.
- Turn on ignition key to start the engine and be sure that the hydraulics is engaged.
- Ensure that the engine reaches 1500 rpm.
- Open the manual relief valve and then lift the tank approximately two feet.
- Get a strong board big enough to cover the opening of the micro-strainer and place it on top.
- Gradually close the manual relief valve until a clattering or whistling sound is heard.
- Inspect the relief gauge from the control panel; it should be within one inch of the recommended rating.
- Replace the relief valve if it fails to open.
It is very important to have regular inspections and testing of relief valves to decrease the downtime of a vacuum operation and unwanted cost while increasing the level of safety. There are various types of relief valves in a vac truck for sale and all of them require regular inspection and testing to ensure proper functioning. By allowing the flow of air through the valves, the pressure in the shielded component is reduced, protecting the entire vehicle from possible catastrophic failure. Hopefully this article has shown why it is so important to check the function of the vacuum truck relief valve!
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