Wednesday, May 3, 2017

What is a Cycling Dryer and Why Would You Want One?

Most plants currently have a dryer that continuously runs and uses a component called a hot gas bypass valve to keep the unit above 38° F and prevent it from freezing up. But, there are many different types of cycling dryers that accomplish the same result without the dryer constantly running.

  • Cycling type with a thermal mass is cooled down to the required temperature and the compressor shuts off – this works much like your refrigerator – if no load, the unit does not come back on until required – very effective and the most reliable
  • VFD cycling uses a variable speed drive on the refrigeration compressor that varies the amount of power/refrigeration used based on the temperature of the air – operates much like a variable speed air compressor – most have a range of 100% to 30% – not good in low range applications – fairly complicated electronically
  • Load/unload cycling compressors – works much like larger refrigeration systems and can be effective when they are fairly steady medium loads – can short cycle with low loads – sometimes not as power cost effective as a true cycling dryer

With that being said, if you purchase a 500 CFM dryer ($8,000) for your plant and left it on while your compressor is running (or maybe you forget to shut it off at the end of the second shift), it would use 2.5 HP continuously. If you purchase the same 500 CFM thermal mass cycling dryer ($10,200) for the same application, it would require 2.7 HP. But, in an average plant it would be on only 20-25% of the time. The cost difference between the two is $2,200 and the savings is $1,490 for $6,000 a year at $.15 a KW. Using simple math, the ROI is 1.5 years.

Other advantages of using a cycling dryer are:

  • You do not have to remember to turn the dryer off when you turn the compressor off as it shuts down
  • Potential freeze up at low load conditions almost eliminated
  • It can be used with lower CFM compressors while maintaining the same dew point
  • It will tolerate higher ambient/higher inlet temperature conditions more readily over standard dryer.
Remember all dryers are rated at 100 PSI/100° F inlet air/100° F ambient temperature. If you increase the air pressure dryer performance gets better. If the ambient air temperature or the inlet air temperature gets above 115° F your dryer could be in big trouble and moisture will soon be invading your system.

If you would like to know more about how a cycling dryer would be a better fit for you than what you have we be happy to help or if you have any moisture issues let us know. Contact Frank Lederer:

Monday, April 17, 2017

Rotary Screw and Piston Compressors On Display at No. Haven Parker Store

Jeff Haynosch

Sales Engineer

It’s exciting that in addition to the fluid power products we have been representing at Connecticut Fluid Power over the years, our joining up with The Hope Group last year has meant that we have expanded our product offering to include fluid connectors, and now, compressed air systems and service.

At the Open House and Technology Seminars on May 10, 2017, at our new Parker Store in North Haven, we will have a display as part of the Trade Show of Kaeser rotary screw compressors and Hope Air Systems’ own brand of piston compressors. Our customers always need a power source, whether it’s a generator, a hydraulic power unit, or an air compressor, and so it’s great to introduce this new line of products to the North Haven area.

You can learn more about the Technology Seminars and the Open House by visiting the website.

Wednesday, March 29, 2017

Don’t Leave Fluid Analysis Until It’s Too Late

Henry St. John
Parts Mgr, Hope Air Systems

Without proper preventive maintenance, your system could experience failures ranging from small to fatal. Routine fluid analysis is important and should be conducted on a schedule to monitor wear, determine potential failures in process, and to schedule fluid changes accurately.

Fluid analysis should not be an optional procedure left to whenever you “get around to it”. It must be routinely conducted by engineers and technicians as a tool to measure and monitor principal fluid characteristics that include metal content, water content, and viscosity.

Hope Air Systems’ engineers and technicians are ready to help with a fluid analysis to prevent costly failures and breakdowns. If you have any questions, please contact me at 508-351-1827 or by email (

Wednesday, March 8, 2017

How to Save Energy/Money By Controlling Your Air Compressors

We recently released our monthly eNewsletter. It contained two important topics about your air compressors that I would like to share with you.

The first article deals with properly controlling your air compressors to save energy and money. Unfortunately, electrical costs are not going down and it is important that one person is responsible for conserving energy in your plant. There are some simple things that you can do to ensure you are controlling your systems properly. To learn more, read the entire article titled: Turn It Off (Your Air Compressor)

Avoid Filter Confusion
The second article talks about avoiding filter confusion. Are you selecting the correct filter? How many filters do you actually need? When tackling this topic, I discuss a basic filter that every system needs down to a filter that may be used in breathing air or biotech firms.
To learn more, read the entire article titled: Filters - How Many and What Do I Need

If you didn’t already know, Hope Air Systems releases a monthly eNewsletter on a wide range of informational topics, such as these, that can help you in your compressor room. If you would like more information on these topics, or would like to receive the newsletter, please contact Frank Lederer at 508-351-1817 or by email ( and he would be happy to assist you.

Wednesday, February 15, 2017

New Reciprocating Compressors Added to Hope Air Product Line

Henry St. John
Parts Mgr, Hope Air Systems

As you know, Hope Air Systems is a proud distributor of Kaeser and Champion Air Compressors. I am excited to announce we are launching our own line of industrial-grade reciprocating air compressors to add to our product line.

The new Hope Air Systems’ stationary vertical or horizontal electric two-stage, belt-driven compressors deliver up to 33.6 CFM at a maximum pressure of 175 PSI and 35.0 CFM at 100 PSI. They are built for commercial and industrial applications and are equipped with an electric Baldor Motor (single phase and 3 phase available), magnetic starters, and cast iron pumps. The patented pump design provides for a cooler running pump. We are also offering gas engine (powered by Honda) and portable compressors.

You can view our brochure (PDF) for details and pricing. Or, if you have any questions call me at 508-351-1827 or email me ( 

In the meantime, take a look at all our reciprocating compressors on our website!

Hope Air Systems V-120 Compressor now displayed in our Northborough showroom

Friday, February 3, 2017

Why Blow Offs Are The Newest Secret Saver

We all know that a pinched copper tube blowing onto a product is a really inefficient way of using compressed air. 

How bad is it? A 1/8 inch hole will flow 26 CFM at 100 psi, which uses at least 6 HP on your air compressor. If you run three shifts five days per week and pay $0.10 per KW, that little piece of copper blow off tube probably cost you around $2900 per year. Many blow offs have smaller openings than 1/8 inch.

There are really three solutions out there to save energy and costs associated with air blow offs.

#1 is to convert to a blower, which may not be feasible in some applications. 

#2 is to put a nozzle on the end of the tube to reduce the flow and the sound level, which works just fine but many of the nozzles disappear after period of time.

#3 is to reduce the amount of air by changing or and inserting a control valve.

Solution #3 is the direction that Parker's Air Saver Unit has taken. It is a valve that converts a continuous air blow to a pulsed air blow without the need for any other external control. Air is blown with a series of ON and OFF pulses. When the blow is OFF, there is no air consumption. By using switching valve technology the Air Saver Unit can reduce air consumption by up to 50%, which translates into:

  • Large reductions in air consumption.
  • Savings in compressor power consumption.
  • Reduction in plant CO2 emissions.
  • Big contribution to energy-saving activities.
  • Improved efficiency.
When you consider that air blowing accounts for up to half of all compressed air used in plants, the potential energy and cost savings is considerable. In the example outline below, the application of Air Saver Unit valve on four nozzles with a one minute below per four minute cycle operating for three shifts, five days per week saved plant operators $3,500 annually.
Sample Application—›4 nozzles
6 mm dia.
+1 min
blow per
4 min
+3 shifts

5 days/

Air Saver Unit Valve Calculator
Summary Sheet
Reduced Total Annual Air Discharge per Blowing Nozzle (cfm) by:3,232,005
Reduced Annual CO2 Emissions Generated (per Blowing Nozzle, in tons) by:5.77 tons
Reduced Annual Air Generating Costs Per Blowing Bozzle by::$892.03
Quantity of Air Blowing Nozzles with Same Application Specifications:4
Reduced Annual Air Generating Costs For All Nozzles by:$3,568.13
Reduced Annual CO2 Emissions Generated (For All Blowing Nozzles) by:23.07

This is the only the tip of the iceberg for air conservation. To find out more about how to properly use this Air Saver valve and other energy conservation components click on the link below to register for the Introduction to Industrial Pneumatics seminar being held from 8:30AM to 12PM on October 20 at the Parker Store in Lewiston, Maine.

Need a system engineer to look at specific air use problem in your plant? Please call Frank Lederer at 508-351-1817 or email: Frank Lederer at

Monday, August 1, 2016

Your Compressor Should Play Well With Others

Many plants today have multiple rotary screw compressors running at the same time. This is a result of requiring additional air and adding another machine.

Unfortunately, often times compressors do not play well together and unless properly set up, this can cause excessive run time on equipment that now requires more maintenance as well as running up the power bill.

The following is an extreme case seen earlier this year of two 300HP compressors that did not play well with each other.

Two 300HP air compressors are operating in tandem to load and unload. The air compressors are rated for 1,325 at 150 PSI and the average flow meter readings from these two machines were 720 CFM or 54% of full load of one air compressor. Both compressors consume a total of approximately 379 kW. At $0.14 per kWh this would equal a yearly cost of $38,000 using a yearly operational load of 8,400 hours. One compressor should be set as lead and the other one as lag with the second compressor only coming on when needed – the potential annual savings of $60,000 from conservation and reduction of pressure can save 115 CFM by shutting off one compressor, which is a total potential savings of approximately $100,000 per year. Investment would be less than $2000 in maintenance or service cost.

While this is an extreme example, he gives you an idea of what could happen if two compressors are running together without any kind of evaluation and control set up. Here are some of the common scenarios that I have seen over the years:
  • Big/little compressor both with modulation control—the big compressor should be set up as a baseload and the little compressor should be taken out of modulation if possible and set to load and unload. It’s very inefficient to load and unload the larger compressor.
  • Two compressors with modulation load/no load controls—modulation unit should always try to be used as a baseload as it is least efficient in any part load situation. The system may need to have an appropriately sized receiver at least three times the volume of the machine. For example, 50HP 200 CFM load unload compressor should have a 660 gallon receiver.
  • VFD compressor used with load/no load or modulation control compressor—always have the load/no load or modulation control compressor as a base load and trim with the VFD unit.
  • Control gap can occur in any system when a VFD unit cannot turn down enough to meet a lower demand and goes to a load/unload scenario being less efficient—this also can cause a second machine to start up due to a pressure drop, which causes the two machines fight each other.
If you are running a 50HP and a 75HP compressor and they are both sharing loads for two shifts five days a week with power at $0.15 per KW, you could potentially be wasting 30 HP or $20,000 in energy costs per year. The savings goes up and down with the connected horsepower of two machines that are not playing well with each other.

The first step is to have your compressor technicians set up the compressors to operate most efficiently for the controls that they have for the average load in your plant. Unfortunately plant loads vary and a control set up done this month may not be appropriate 90 days from now.

A more comprehensive solution would be to evaluate your compressor system for usage and determine if the existing units can be run efficiently with a simple microprocessor control panel. You may also have to add receiver capacity and certainly look for air abuse as well as leaks in the plant.If you have a big compressor and a little compressor and they both seem to be working their hearts out and they didn’t use to, then you may have a control problem. Take the time to get a qualified person to look at them and give you the best advice on how to run your system. This could save you a substantial amount money over the next three years.

There will be more articles on screw compressor control types to follow.

Need some assistance? Please call Frank Lederer at 508-351-1817 or email: