Here's a hint: it has to do with your breathing air respirator.
If you’re in the market for a complete blast machine package, there are a few choices you need to make, such as whether you want a High Pressure (HP) or Low Pressure (LP) package.
Don’t be fooled into thinking you need a high pressure blast machine to operate at high pressure—all blast machines require a minimum amount of pressure to operate.
When it comes to high pressure vs. low pressure, the distinction doesn’t actually have anything to do with the blast pot itself: HP and LP designate which type of breathing air respirator you would like with your package.
Let’s say, for example, you know you’d like a 3 cuft capacity blast machine with 1-1/4” piping. Choosing a complete package would give you the necessary components to begin blasting (minus the air supply and blast suit, for example). If you don’t want an Automatic Cutoff Switch (ACS) on your remote control, you have two options: “ Clemco Model 1648 HP Complete Package, 1-1/4 inch Piping” and “Clemco Model 1648 LP Complete Package, 1-1/4 inch Piping.” For all intents and purposes, these packages are identical except for one very important component: the respirator.
In the case of the HP package, the included breathing air respirator is a high-pressure system. This means that the respirator is fed by an air compressor and filtered with a CPF-20 Breathing Air Filter. Although this option is generally a little higher in price, it is most likely the type of system you will need.
The LP package, on the other hand, includes a low pressure breathing air system. This LP respirator requires a separate ambient air pump to supply the breathing air to the respirator. While this package is typically cheaper, it requires an ambient air pump. Typically, operators who don’t already have an ambient air pump prefer the HP system that works with their compressor.
However, it is worth noting that you can convert an LP Breathing air respirator over to HP with a conversion kit, but doing so may cause delays (and will cost more money).
At the end of the day, choose whatever system works best for you and any setup you already have. Just keep air quality in mind, too. For an HP system, make sure your air compressor is capable of delivering Grade D breathing air. Using a CO2 monitor adds an extra level of safety when it comes to your breathing air. (You can read about the dangers of carbon monoxide poisoning here) When using an ambient air pump with an LP system, make sure the pump is placed in a clean environment upwind from exhaust and other air pollutants.
Need help choosing the right compressor? Check out our post, Understanding Sandblasting Compressor Size Requirements.