Which Roughing Pump Is Right For My Application?

A roughing pump is a vacuum pump used to evacuate a vacuum system to achieve a high vacuum or ultra-high vacuum. The term roughing-pump is gotten from the range it operates in, 0.1 Pa. There are two categories of roughing pumps, dry and oil-sealed roughing pumps. There are different types of designs you can pick from the two categories. You could choose a pump based on the vacuum level, cost, lifespan, and maintenance.

Choosing the right pump can be cumbersome and time-consuming. This is because you have to make multiple comparisons. If you are not sure about what pump will work best for your application, you can always consult with professionals. High Vac Depot has a range of pumps you can choose from, and we also offer engineering consultation services. Listed below are a few factors to consider when selecting a vacuum-pump.

Backing Role

When choosing a pump for your application, the most vital factor to consider is the backing role, especially when the ultimate goal is a high vacuum. For a turbo drag pump to operate efficiently, it must be within a particular pressure envelope. Ensure that the pump’s inlet pressure is sufficiently low for the pumping arrays to accord a large transfer to the gas molecules being pumped slowly from the system.

The molecules are usually compressed via the pump, and with reduced pressure, they get exhausted in another place. The backing pump will then remove them actively, sending them out into the atmosphere. Make sure you constantly monitor the foreline pressure. For the vacuum to quickly compress the air that comes in through the inlet, the foreline pressure must be low enough.

Balance Between the Operations

When this pump is in motion, it performs two precise operations. First, it rough pumps the whole chamber to change the atmospheric pressure to relatively low pressure. Doing this ensures that the high vacuum-pump works smoothly. Once the process has begun and is underway, the pump reverts to its other position, which still supports the high vacuum except that it now provides the pump with low pressure for it to exhaust from the outlet.

You will have to consider how much time the pump will take to change the atmospheric pressure to provide low pressure. If the efficiency is high, that is excellent for the pump. If the use of a high vacuum is on-demand, but you do not use it consistently, it would be best if you added a vacuum hold tank, so the pump pumps down the tank, and whenever the vacuum is needed on-demand, you can remove it from the tank. Doing this will add to your pump’s longevity since you will have reduced the number of times the vacuum has to start and stop. You can burn your motors up if you frequently turn the pump on and off.

Specifics of the Pump

When choosing the right pump for your application, it is essential to take your process into account. For instance, think of factors like whether the pump will be near people and if it does not have to produce any sound or oil mist, will any corrosives be pumped into the pump, and the volume of condensable that you will have running into your pump. There are also various fittings, purges, and types of seal available to address corrosive chemicals or condensable that will be in the process. This often adds excessive wear and tear to the traditional designs of pumps.

You can purchase external accessories like inlet filters and inlet traps, which can help get rid of the chemicals before they enter the pump. However, you need to know that this can affect the speed and efficiency of the pump. External exhaust mufflers and filters are usually used to reduce the noise and knock down the oil mist that is in the laboratory environment.

Pump down Cycle

A backing pump and a high vacuum-pump work together so that the whole process can work how it is supposed to. Therefore, you need to ensure that the units can work in tandem to give off the required pump-down curve when buying a pump for your application. To produce this effect, the backing pump’s power has to match that of the high vacuum-pump. The best thing to do is to check the high vacuum pump’s specifications before purchasing a backing pump. As aforementioned, there are different types of backing pumps that you can choose from.

Note that they all produce different pumping curves. For instance, you may find the same flow rates and ultimate vacuum in a multistage piston pump and two-stage oil-sealed vane pump, yet you will notice that they have a different pump down curve. Therefore, they will all fit particular applications. The same applies to dry scroll pumps and dry multistage roots. So you need to ensure that you have analyzed the operations in which your pump will be operating, so you have a clear understanding of what pump will fit your application best. The technical specification and pump down curves given by a manufacturer often reflect the best-case scenario in an excellent condition. Consider factors like the load volume, process constituents, operating temperature, and frequency of the operation.

You need to consider that if you use the wrong backing pump, you can negate all the work you put in choosing a high vacuum-pump because it will be operating outside its main performance level. Ensure that the pump you select for your application can work hand in hand with the high vacuum pump. Both the dry and oil-sealed pumps have their advantages and disadvantages, so you will need to know this to make an informed decision when picking the right pump for your application. Here at High Vac Depot, we can help you with all of your vacuum needs. We have a wide array you can choose from, and we are professionals, so we can help answer any questions you may have. We will also ensure you get a pump that is right for your application.