Tag: plumbing

Consider these Variables When Choosing Compressed Air Pipe Size

Published on by Brian FarnoLeave a comment

Here on the EXAIR blog we discuss pressure drops, correct plumbing, pipe sizing, and friction losses within your piping system from time to time.   We will generally even give recommendations on what size piping to use.  These are the variables that you will want to consider when selecting a piping size that will suit your need and give the ability to expand if needed.

The variables to know for a new piping run are as follows.

  • Flow Rate (SCFM) of demand side (products needing the supplied compressed air)
  • System Pressure (psig) – Safe operating pressure that will account for pressure drops.
  • Minimum Operating Pressure Allowed (psig) – Lowest pressure permitted by any demand side point of use product.
  • Total Length of Piping System (feet)
  • Piping Cost ($)
  • Installation Cost ($)
  • Operational Hours ( hr.)
  • Electical Costs ($/kwh)
  • Project Life (years) – Is there a planned expansion?

An equation can be used to calculate the diameter of pipe required for a known flow rate and allowable pressure drop.   The equation is shown below.

A = (144 x Q x Pa) / (V x 60 x (Pd + Pa)
Where:
A = Cross-Sectional are of the pipe bore. (sq. in.).
Q = Flow rate (cubic ft. / min of free air)
Pa = Prevailing atmospheric absolute pressure (psia)
Pd  = Compressor discharge gauge pressure (psig)
V = Design pipe velocity ( ft/sec)

If all of these variables are not known, there are also reference charts which will eliminate the variables needed to total flow rate required for the system, as well as the total length of the piping. The chart shown below was taken from EXAIR’s Knowledge Base.

Piping
Airflow Through 1/4″ Shed. 40 Pipe

Once the piping size is selected to meet the needs of the system the future potential of expansion should be taken into account and anticipated for.   If no expansion is planned, simply take your length of pipe and start looking at your cost per foot and installation costs.    If expansions are planned and known, consider supplying the equipment now and accounting for it if the additional capital expenditure is acceptable at this point.

The benefits to having properly sized compressed air lines for the entire facility and for the long term expansion goals makes life easier.   When production is increased, or when new machinery is added there is not a need to re-engineer the entire system in order to get enough capacity to that last machine.   If the main compressed air system is undersized then optimal performance for the facility will never be achieved.   By not taking the above variables into consideration or just using what is cheapest is simply setting the system up for failure and inefficiencies.   All of these considerations lead to an optimized compressed air system which leads to a sustainable utility.

Brian Farno
Application Engineer Manager
BrianFarno@EXAIR.com
@EXAIR_BF

Undersized Plumbing Creates a Performance Problem

Published on by Lee EvansLeave a comment

Sometimes we get calls or emails from our customers experiencing a problem with their application already using EXAIR products.  These calls can range from difficulties associated with installation angle, installation, or, in many cases, the compressed air plumbing to the product itself.

That was the case in the application of the photos above.  The end user had been using our model 6084 Line Vac to move plastic pellets from the floor to the top of a machine hopper, and they needed to increase the flow.  The problem, was that they weren’t getting the performance from the 6084 that they thought they should.

Chip Vacuum 1
                                                                 EXAIR model 6084 Line Vac used for conveying plastic pellets

 

Chip Vacuum 2
Model 6084 Line Vac used to convey plastic pellets from the floor to the top of a machine hopper

 

Given the bulk density of the plastic pellets in this application, the end user should’ve been able to move more than enough material in the time they desired for the application needs.  But, instead, the Line Vac was moving little-to-no material and even “stalling” – a condition in which the conveyed material could enter into the Line Vac and then cease to convey.

What we found, after exchanging contact information and discussing the photos above, is that the compressed air line feeding the Line Vac is too small, creating a pressure drop and leading to an inadequate compressed air flow.  This, in turn, leads to lower air velocity at the exhaust of the Line Vac, which simultaneously means lower vacuum and material flow at the inlet.

The end result is the condition described by the end user – a low flow, or no-flow, of the material being conveyed.

After our discussion the end user set out to make the required change to the supply line, providing proper flow to the Line Vac at the proper pressure, and moving the material as required.

It’s always rewarding to help an end user solve their problems.  If you have an application problem and think EXAIR might be able to help, contact an EXAIR Application Engineer.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

Proper Plumbing Makes Full Flow Air Knives Operational

Published on by Lee EvansLeave a comment
Full Flow Air Knives for plate drying
These EXAIR Full Flow Air Knives were in need of an EXAIR Application Engineer’s expertise

Sometimes we get calls or emails from our customers that need help.  Help can be in the form of product selection, heat load calculation, or proper installation.  I had one such interaction with an end user of our Full Flow Air Knives, using them in the manner shown above.

The problem they were having was poor flow and low force from the blow off.  We originally discussed the application over the phone, and after suspecting a plumbing issue may be at play, I asked for a photo.  I received a quick photo of their setup and immediately saw the two knives were poorly plumbed.  The clear/light blue hose, and the dark blue hoses in the photo just aren’t big enough for two knives of this size.

When installing any compressed air driven product, pressure and flow are the name of the game.  Sometimes, as in this case, there was good pressure at the gauge (which, if checked at the inlet of the knife would have shown a significant pressure drop), but there just wasn’t enough flow.  The root cause was diameter of the piping used to deliver the air from the main line to the point of use.

Once the compressed air line sizes were increased, the knives worked flawlessly and the end user could use them as intended – which was blowing debris off of a plate fed through the middle of the two knives.

If you have an application that you think may have a plumbing concern, or any other need for EXAIR products, contact an EXAIR Application Engineer.  We’ll be happy to help.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

Quick Disconnects & Why Not To Use Them

Published on by Brian FarnoLeave a comment

Quick Disconnects are a quick and easy solution to hook up devices to your compressed air system.  These units can be found in quite a few factories and are more often than not being used incorrectly.  I know that on the air compressor in my garage, the only way to hook anything up to it was to use 1/4″ quick disconnects.  Chances are they are even a few of them within your facility, assuming you have compressed air available.

1/4" Quick Disconnect male and female.
1/4″ Quick Disconnect male and female.

When you really look at a quick disconnect though you start to see why it shouldn’t be used to install every compressed air driven device there is.   You can see in the pictures below that a 1/4″ quick disconnect that goes to a 3/8″ NPT adapter has a .192″ opening at the small end.  A 3/8″ Schedule 40 iron pipe will actually carry a .493″ inner diameter.   If you were to use this quick disconnect on something like a 2″ Heavy Duty Line Vac, you will starve it for air due to the limited ability of the small diameter to carry enough air volume. This, in turn, will limit the performance of the Line Vac.  This is because the through hole on the quick disconnect cannot pass enough air to feed through to the Line Vac.

Inner Diameter of 1/4" quick disconnect.
Inner Diameter of 1/4″ quick disconnect.

On the 1/4″ quick disconnect to a 3/8″ NPT this may not be as large as a problem as the next picture.  Below you can see a 1/2″ quick disconnect that is going up to a 3/4″ NPT.  a 3/4″NPT Schedule 40 iron pipe is actually a .824″ inner diameter.  The quick disconnect at most has a .401″ inner diameter.

IMG_4614
1/2″ quick disconnects

 

Inner diameter of 1/2" quick disconnect.
Inner diameter of 1/2″ quick disconnect.

Even though you are providing the correct thread size for your connection (a 3/8 MNPT and a 3/4 FNPT respectively in our example) the quick disconnect’s small inside diameter could be too much of a restriction for the volume demanded by an end use product. Due to this restriction point you will see pressure drops in your system when using a device with a properly sized inlet for its demand of compressed air being fed with an improperly sized quick disconnect.  This is one of the main reasons one of our first questions in troubleshooting an EXAIR products performance with a customer is whether or not they are using quick disconnects.

If you would like to learn more about how to properly plumb your EXAIR Intelligent Compressed Air Product, feel free to contact us, or take a look around our Knowledge Base.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF