It is often worthwhile to get a whole package from a specific compressor vendor (compressor and dryer) as a single source for a system, and equally important in my view, a single source for warranty and maintenance as time goes on and things start to fail.
For example, is the type of compressor drive important to you?<.p>
Consider that the compressor might have a 'V' belt drive, a variable speed drive, or be direct driven. Consider the up-front cost of each drive type as compared to the long term maintenance costs to keep that style of air compressor running. Which best suits?
There is a filter to clean the air entering the compressor intake.
There should be a auto-draining compressed air filter at the receiver discharge line to the plant.
The oil used in the compression of air will need to be filtered.
Determine up front what types of filters comes with your compressor, and what filtration you will have to add after the fact.
Questions that should be answered up front include:
All of these questions should be considered before you make your compressor choice.
A run-time hour meter is very useful for monitoring compressor use, and having one is key to helping ensure that maintenance is carried out at the appropriate intervals.
If you compressor doesn't come equipped with this, make it a point to ask for it./p>
How does the maintenance person check the lubrication levels on this compressor?
How many different types of lubricating oil does this specific compressor have?
Ask the compressor vendor what options you have for lubrication, what their recommendations are, and how stepping outside of their recommendation (perhaps you're convinced that another synthetic oil will work better for you) will affect your warranty.
Whether it's a simple sight glass, right up to a pressure and temperature oil sensor with alarm function, if your compressor contains oil, you'd best make sure you can check it easily.
Typically compressor lubricating oil is not good for downstream components, often degrading rubber seals and polycarbonate air components. Ask about percentage of oil carryover a particular compressor has, how time affects the air / oil separation efficiency, and how best, with that type of air compressor, to keep compressor lubricating oil out of your air lines.
Carrying is OK for a small HP unit, as they might only weigh 40-50 pounds. As your CFM needs increase, so does the horse power, and larger HP means more weight.
Consider a wheelbarrow type construction for slightly larger compressors. Or even a fork insert area whereby you could lift the unit with a hand or powered fork truck should it be necessary to move the compressor.
Portable tow-behind air compressors have portability built in. Maintaining the trailer part of that compressor is something you want to know about up front.
If your air compressor needs to be moved, how will you do it?
Excessive vibration is a symptom of major failure in the system and you will want to know about it immediately if compressor vibration starts to occur. How will you?
If there are too many reasons why a particular compressor manufacturer's warranty would not be honored by them, well, it's like having no warranty at all, isn't it?
I hope that the list of more compressor accessories isn't too overwhelming. Certainly, it is a good idea to consider everything when acquiring a new compressor that may be worth north of tens-of-thousands of dollars.
Take your time and investigate compressor accessories thoroughly. Years after you buy your compressor, having done so will continue paying dividends.