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Category: Air Compressor

Safety Guidelines When Using an Air Compressor

From industrial equipment, power tools at home, paint sprays and so much more, air compressors are now widely used. The range of compressors from Peerless Engineering include some of the most famous types in the market. Although air compressors can now easily be found in homes, the risks and dangers they pose should not be overlooked. If used safely, our air compressors can offer you a lot of benefits. Here are some precautions you can take when using them.

 

How to Prevent Bodily Harm

Compressed air can be dangerous, therefore it should never be directed at any person’s skin. An injury can occur even on a low pressure. It might be tempting to clean dirt from another person or yourself, but never do it. Compressed air is not intended for breathing or inhaling, unless it comes from a system that has been specifically designed for breathing, and has a proper air filter and regulator in place.

Always wear safety goggles or any suitable face shield while cleaning with an air compressor to prevent damage to your eyes. You should also wear ear protection, as using compressed air can be noisy.

 

How to Care for the Hoses

Pressurized hoses should always be treated with care. When under pressure, they should never be coupled, uncoupled, or crimped. Before you connect or disconnect hoses, make sure that all valves are bled down and all valves are switched off.

Before using air, always make it a point to check your hoses. Inspect them for damages before starting your task. When storing away your hoses, find a storage place that is away from direct sunlight  or any heat. If you can store it on a reel, damage is significantly minimized.

 

Safety While Using an Air Compressor

Follow the OSHA regulations for cleaning with compressed air. For safety reasons, The pressure should not go beyond 30PSIG. You must also inspect if you have used the correct clamps and fittings on your air hoses. Using the wrong ones can be very dangerous.

It is also important to make sure that the end of the hose, where the compressed air is coming out from, is securely held at all times. If they aren’t, the hose can be detached and can whip around. This can easily cause injuries.

Keeping Contaminants Out of Your Vacuum Pumps

Vacuum pumps take in any and all contaminants that come in from the pump inlet. There are four relevant forms of contaminant:

  • Vapors
  • Liquids
  • Solids
  • Biological Agents

Vapors
There are some vapors that can pass through a vacuum pump without harming it; all others should be passed through a condenser to convert from vapor form into liquid, and then drained off before they can make it into the pump. That’s because even small quantities of vapor can take up large volumes, distorting the effects of a vacuum pump or air compressor.

If the pump casing fills with vapor, it can condense inside the pump, which can overload the motor and damage the pump. Also, if the vapors condense within the water ring, the vapor pressure of the water seal will rise, which can encourage cavitation.

A good recommendation is that a ‘cold wall’ condenser be put in line before the liquid separator (see below) unless the vacuum pump uses a steam ejector to produce the vacuum, in which case no condenser is needed except where extreme efficiency is mandated.

Liquids
Liquid condensing inside the vacuum pipeline — or worse yet, in the pump itself — can require a complete disassembly of the pump. Depending on the kind of water suspended in the vacuum stream, different tools may be necessary:

    A water trap or knockout pot for visible ‘slugs’ of water and suspended aerosols

  • Or a cyclonic separator for water vapors and other particles that are not particularly heavier than the air itself.

Either one of these should be installed after the condenser but prior to the vacuum pump intake.

Solids
Solid particles are filtered out with exactly that — filters. Filters come in paper, hydrophobic, synthetic fiber, fiberglass, metal mesh, or other more exotic types, but they all have the same basic purpose: to let air through while keeping solid particles suspended in the air trapped in the filter. Most industrial purposes require either high-efficiency particulate air (HEPA) or ultra-low penetration air (ULPA) filters. Such filters should be installed prior to the condenser.

Biological Agents
In most cases, a HEPA filter will take care of 99.9% of biological agents. Even given that fact, every wet vacuum pump should be configured in such a way that it can be quickly and safely sanitized — and it should be sanitized regularly, at least twice a year, even if no sign of biological contamination has been noted.

Vacuum Pumps vs. Air Compressors: What’s the Difference?

In theory at least, vacuum pumps are ‘merely’ air compressors run backwards — with the inlet attached to a machine you want to apply vacuum to and the outlet open to the air. In fact, for smaller, at-home uses, an air compressor and a vacuum pump are literally the same machine, you just decide which end you want to use and attach whatever your attaching to the appropriate end.

In industrial uses, however — in sizes that affect entire machining plants or other large-scale operations — the machines differ in small ways that enhance the efficiency of one operation over the other. And only very specifically-made machines should be used as both a vacuum generator and a compressor at the same time; the doubled load will run any machine not carefully built to withstand it.

There are three things you need to know about a vacuum pump: the strength of the vacuum it can produce, the rate at which it moves air, and the amount and quality of electricity it takes to use.

Vacuum Strength
Vacuum strength is measured in absolute pressure (mmHg), where the smaller the number, the power powerful the vacuum. Standard atmospheric pressure is 760 mmHg at sea level, so anything less than that is a form of vacuum. Most large pumps are rated once, for continuous-duty use. Small pumps, which can have problems with overheating at high loads, usually have a continuous-duty rating and an intermittent-duty rating showing how much it can produce for short times before it needs a break.

Flow Rate
Vacuum pumps are flow rated according to how quickly they can move air when both sides of the pump are at equal pressure (i.e. open to the air.) Of course, as the vacuum on one side of the pump increases, air flow decreases. Manufacturers can provide the curves that show what the flow rates should be as the vacuum increases.

Power Requirements
Vacuum pumps use relatively little power compared to air compressors. The aforementioned pressure-flow curves should also include the amount of drive power required as the vacuum levels change (and thus allow you to derive efficiency rates by dividing power needed by air moved at each point along the curve.)

A Word On Laboratory Air Compressor Systems

medical air compressor system does not necessarily make a good laboratory compressor system.  Medical air compressor systems are designed to deliver clean, 50 psi, breathing air as specified by a CSA Standard.  Laboratories may not be best served by a medical air compressor.  Here are some things to think about when procuring a laboratory compressor system

OIL-LESS VERSUS LUBRICATED

Oil-less air compressors are expensive relative to lubricated compressors.  Today’s tight budgeting has required the installation of lubricated compressors in laboratories where the low risk of compressor lubricant in the compressed air is acceptable.

PRESSURE

The 50 psi pressure supplied by a medical air compressor is often not enough for a laboratory.  Laboratory equipment may require 80 to 120 psi pressure.  Determine from the user what pressure is required.  A compressor running start/stop will need to shut off at a pressure 20 to 40 psi above the required pressure to allow for pressure switch  differential, purification pressure loss, pressure regulation and pipeline pressure drop.

CUBIC FEET FREE AIR PER MINUTE VS. CUBIC FEET COMPRESSED AIR PER MINUTE

Compressors are usually rated in CFM free air.  This should be the quantity of air delivered referenced to the compressor inlet conditions.  Cubic feet compressed air equates to free air as follows

Hence, at 80 PSIG, 35 CFM free air equals 5.4 CFM compressed air.

Years ago Peerless Engineering was requested by a consultant to supply a 10 HP, 35 cubic feet free air per minute compressor to a laboratory facility.  It was determined after installation that 35 cubic feet compressed air per minute was required.  To quote Homer Simpson “Do’h!”

The solution was to install a second 50 HP, 175 cubic feet free air per minute compressor.  However, the building was plumbed with only ½ inch compressed air lines.  To quote Homer Simpson again “Do’h!”.

DELIVERED CUBIC FEET VS. INLET CUBIC FEET

Some compressor manufacturers rate their compressor by inlet cubic feet per minute which equals delivered air divided by the volumetric efficiency.   Given that the volumetric efficiency of a compressor can be 70%, rating a compressor by inlet cubic feet per minute makes that compressor look much better to the naïve.

DEW POINT

Compressed air dried to a pressure dew point of -40°C by a desiccant air dryer costs more to make than compressed air dried to a pressure dew point of +4°C by a refrigerated air dryer.  Many laboratories only require compressed air with an acceptable relative humidity at maximum pipeline pressure and minimum pipeline temperature.  This can often be accomplished by a refrigerated air dryer at a lower cost.

Follow Ron Magnolo on Twitter @ronm_peerlesse.