There are several jobs and projects that require the use of a vacuum. One example is extracting oil from a boat’s engine, which is different from a car’s engine. With a car, you can drain the oil from the bottom of the engine, but this is not possible with a ship’s engine. Instead, you need to pump the oil out using a pump. For many years, we used a manual liquid pump consisting of a sturdy container and the hand pump from our inflatable rib, which can also suck air. However, we also need a vacuum for degassing epoxy and silicone for some of our projects.
What is a vacuum pump?
A vacuum pump is a mechanical device that removes air or gas molecules from a sealed chamber, creating a low-pressure environment. Different types of vacuum pumps cater to various requirements. The most common type is the Positive Displacement Vacuum Pump, which physically traps and transports air or gas from the inlet to the outlet. There are also Momentum Transfer Vacuum Pumps that use high-speed jets of fluid or rotating blades to transfer momentum to gas molecules. And, Entrapment Vacuum Pumps capture gas molecules by adsorption or condensation on solid surfaces.
In our shop, we have a vacuum pump with one chamber/stage. It can handle 4 CFM and create a vacuum of 5Pa. The engine has a power of 1/3HP.
What Does CFM Mean?
CFM is an acronym for Cubic Feet per Minute. CFM measures the volume of air, in cubic feet, for each minute it moves. In the case of an air compressor, CFM indicates how much air can move per minute. For example, an air compressor’s output rated for 30 CFM means 30 cubic feet of airflow per minute.
Connection thread.
Our vacuum pump was delivered with some parts for servicing and maintaining air conditioning systems, including hoses and a manifold gauge set. However, we also had to create some additional supporting parts. During the process, we encountered some confusion while trying to identify the type of thread used in the connector on the pump and hoses. After conducting extensive research, we have determined that SAE Thread 7/16″-20 UNF Fit Tube OD 1/4″ (also referred to as SAE 1/4) is the appropriate thread type used for vacuum purposes.
We found connectors that we can use in our 3d Printed tools to connect the hose directly to it.
In Autodesk Fusion 360 you need to make the following thread type:
ANSI unified Screw Threads
size: 0.4375 in
Desgination 7/16-20 UNF
To make it fit you should modify the face offset of the thread with -0.5
Improvements
We will continue to use the vacuum pump in its current state, but we plan to upgrade the exhaust filter in the future. An exhaust filter is a device that ensures that the oil-lubricated vacuum pump releases clean air through its exhaust. It captures and removes any oil mist produced during use, preventing it from being expelled through the exhaust. This causes the oil particles to combine and return to the system, helping to maintain the pump’s efficiency.