To Roger P and others: Compressors Pros and Cons u

Thank you very much for your inputs.

Here is an update for our purchase status and current situation. Our current air demand is at approx. 35 cfm average and peak 60 cfm.

We have filtered many quotations and end up two options: 1) CompAir HV07RS Hydrovane and
2) Ingersoll Rand UP5-7-8 Rotary Screw

I do understand basic pros and cons for both types from this discussion room. But things I need help now is the power consumption when they are off load and the air quality.

Power consumption: Ingersoll Rand salesman said to me that 7kW RS will take 7kW when it is on load and 3.5kW when it is off load, but 7.5kW RV (50%) will take 7.5kW when it is on load and 5.25kW (70%) when it is off load. Is this about right?

Air Quality: We wish to have oil and water free air in the system. Which one will provide better quality?

Please share your porfessional input with me again. Or, any input from any one in this discussion room will be also appreciated.

Many thanks!

ALBERT

Nothing to choose between the different types for air quality, as all oil lubricated compressors will pass a few parts per million of oil even when new. Both compressors will produce water condensate in equal amounts, given the same operating conditions. It is a product of the amount of air being compressed and its humidity, not of the compressor design.

That IR looks like it would be a decent machine when it came time for service. It has a spin on oil/air separator, like an oil filter, so changing it would be a snap. Nicely laid out. Are you looking for a 50 Hz machine though? That's what the pdf file says it is.

Looking at that Hydrovane, it seems to indicate that it is a variable speed version, which would indicate to me that it would be more energy efficient than the other, but I'll take them at their word. I think a Kaeser would beat them both in energy efficieny though.

For me, I'd go with the Hydrovane, due to the lack of gears, pulleys, belts, separate piping and things. Make sure you are getting a turn-key compressor too, and that you aren't getting stiffed for motor starters and the like.

Conside the warranties on both before you decide though.

Before I read your message, I"ve just signed the purchase order for 2 10hp variable speed Hydrovanes with lead/leg system based on the similar facts.

You have just made my day and telling me I did make a correct call. =)

Albert

Be sure and factor the cost of dryers and filters into the cost of the unit, you or managment doesn't want any last minute surprises nor do you want to later have to go back and spend more money to solve a problem that should have been taken care of from the getgo.

Charles

Over the last few years I have heard probably a couple of dozen significant complaints about hardware faults and/or poor dealer service from people who recently purchased small to medium-size IR compressors. These stories are "anecdotal" and I've only heard the story-tellers' versions of the events leading to their dissatisfaction, but there's enough "smoke" to make me cautious.

I'll suggest that you'd be smart to have your IR dealer provide you with names of his recent customers for the compressor you are considering, and that you talk to those references to see how satisfied they are with the product and service.

When you do that, be alert for hints of dissatisfaction . . . you can bet that the dealer "cherry picked" when he provided the references.

John

Second, ambient conditions (temperature & humidity) dictate if a dryer is needed, not the type or brand of compressor. Oil-free compressors remove any concern regarding oil.

First, your demand is not that high but high enough to warrant doing it right rather than doing it multiple times.

I strongly suggest you seriously engineer your system around both your current requirements as well as FUTURE NEEDS (these are what 99.9% of forget about and wind up paying for many times over). You say your current needs are 30 cfm normal with 60 cfm spikes, if I recall from your post. 30 cfm can be handled quite easily with a recip compressor however when you get over about 45 cfm, you begin loose efficiency in several ways. First, the machine will be running at capasity as in wide open throttle which means it'll be running hotter and promoting advanced wear on the internals. This can be countered somewhat by adding an oil cooler, air cooler, ect but you're also adding considerable hardware cost and operational maintenance costs as service intervals will need to be much shorter.

Without knowing your exact requirements, there is no way I can make any judgement on what machine(s) you need. Engineering a compressed air system is far more than just picking a compressor with the capasity to handle the load. Distribution piping must be properly sized & designed which may include additional storage units at key points, positive looping and so on. You may be better off in the long run having higher start-up costs by investing in two compressors, one a recip, the other a screw both working in tandem on the single system. On the other hand you may be best suited with two completely separate systems or a combined dual system. Then again, your application may be handled by a dual unit recip or may be even more efficient and cost effective operated on a single screw.

You obviously have a requirement that definitely warrants further consideration by a qualified application designer. DO NOT rely on sales idiots to design your system because if they were designers, they would not be working as a salesman. Now, there are compressor companies that have a design engineer on staff who is qualified to design the system and size the unit(s) properly in exchange for buying their product. Other companies will direct you to the third party engineering who you will have to pay for their services. In either case, you must CYA by getting in writing a guarantee that will protect you if the system does not perform as designed. You also need to provide in writing your current as well as your future needs BEFORE any design work is done otherwise your engineering guarantee is useless if you try to collect.

Side note: I have first hand experience with an IR T-30 25 Hp recip compressor and without writing a novel on what was wrong with it out of the box, I will simply say that I have no interest in purchasing anything with "I-R" on it anymore. I really don't know what happened to this company but they definitely are not what they used to be.