Don’t Restrict The Flow

June 28, 2016Ken Bean

It seems most every plant I visit has a low pressure problem somewhere in the plant. I’ve written before discussing how pressure flow controllers (PFC) can help with low pressure it certain situations but today I wanted to look at a more common problem. Inadequate pipe size can be a major contributor to low pressure problems in the plant.

Physics dictates that only a certain amount of product, whether it be compressed air, gas or water, will flow through a certain diameter pipe. Also, regardless of the flow being moved the friction of movement causes pressure drop. The more flow that’s attempted to be pushed through the pipe the higher the pressure loss.

I typically see the problem where a plant started with good intentions and design practices but as the plant expands, the main headers and subsequent drop lines are still being used from the original plant air piping system. There is also the case where the original piping was just not large enough to accommodate the flow and the problem gets progressively worse as the years go by.

An often used fix for the problem is to simply set the discharge pressure on the compressor to a higher level which for a period of time will result in a higher pressure reaching the use point. However, as we’ve previously discussed, this solution costs money. Lot’s of money! Therefore the maximum pressure drop should be limited to approximately 1 1/2 PSI between the compressed air system discharge (outlet of the last filter) to the point of use.

The size of the pipe is not the only contributing factor in the plant. Every item within the piping system also plays a very important factor. Consider that each bend (45 or 90 degree) also adds to the limit of the flow through the pipe as well couplings, flex hoses, and quick connects. When all the restrictions are added up it can amaze the end user just how much restriction is in the piping distribution system.

When reviewing the piping system the following items must be taken into account:

Diameter of pipe
Length of pipe
Number of bends couplings (other restrictions)
SCFM of air required to be passed.

First ,determine the flow from the compressor. This should be a standard rating given by the manufacturer usually in SCFM or Standard Cubic Feet per Minute at a given pressure. It’s wise to note that the SCFM rating by the manufacturer is the flow the compressor can deliver at a standard condition. Meaning the compressor will deliver a given SCFM of air at 68 degree F and 20% relative humidity and if you are reviewing a dynamic compressor, the elevation is also taken into consideration. When any of these parameters are changed then the delivered air by the compressor changes as well.

Next, review the chart below, finding your pressure rating in the left hand column and matching it to the pipe size being considered from the top row. The intersection point of these two data items shows the amount of air that can be delivered through the pipe with the stated pressure drop.

Also, remember that the table shows information for straight pipe runs. It does not take bends, couplings, tee’s or other restrictions into account. A pipe with one 90 degree bend will have a greater pressure drop than a straight run of pipe. If the pipe run has 1 bend and 1 tee then the pressure drop will be even higher. The simplest way to add these restrictions to the calculations is to use “equivalent pipe lengths”

The table below shows elbows, Tees, Returns and valves for various size pipe. Adding one of these items equals adding a certain length of pipe to your piping system. For example: adding 1 long radius 90 degree elbow to a 3″ pipe would add a restriction to your piping system that equals 3.4 feet of additional pipe which can be added to the total pipe length in the table above.

Knowing the flow capacity of your compressed air piping distribution system is a critical aspect to achieve maximum efficiency for your system. The slightest change can create a major end result when you’re dealing with thousands of feet of pipe. Even the type of pipe and connections make a difference in flow restrictions.

For new systems where the number of restrictions is unknown, a general rule of thumb is to multiple the total estimated pipe length by 5.5 to estimate for bends, couplings and valves.

When in doubt, it’s always best to consult your compressed air professional for assistance.

Do You Have a Matched System

April 12, 2016Ken Bean

Simply put, does the drawing left of the red line (Supply) match the right side (Demand) in terms of air flow and pressure? Does it continually match? Likely it does not as demand is in constant fluctuation whether from changes in use, shift change or downtime.

Within a compressed air system, the system dynamics (changes in demand over time) are especially important. Using controls, storage, and demand management to effectively design a system that meets peak requirements but also operates efficiently at part-load is key to a high performance compressed air system.

In many systems, compressor controls are not coordinated to meet the demand requirements, which can result in compressors operating in conflict with each other, short-cycling, or blowing off are all signs of inefficient system operation.

As in most relationships, the key is communication. Communication between the compressors so that each (or a central controller) knows the status of all the other units. Communication is also key between the compressors (or central controller) and the demand side of the system. The compressors perform based on information from a pressure sensor located downstream of the compressor discharge. But where is this sensor located?

A common mistake is the pressure sensor is located close to the compressor discharge. Perhaps even before the dryer. If this is the case in our system drawing above, you can see that the compressor is performing based on pressure data before the air enters the dryer or the subsequent filter, both of which have pressure drop as air passes through. This drop can range from 5 PSIG up to 12 PSIG or higher depending on how well the system was designed as well as the condition of the filter element. A dirty element near the end of it’s life will have substantially more pressure differential than a clean filter element.

If the compressors are discharging at 100 PSIG and there is a 10 pound drop through the dryer and filter, then the plant is only receiving 90 PSIG and this doesn’t include the pressure drop throughout the plant piping system. When a cyclical event occurs, such as several blow guns operating at the same time, the pressure drop has to travel back through the entire system before the compressors see the event and can respond to correct the drop in pressure by increasing their output.

All factors must be considered when designing or updating a compressed air system. Your best course of action is to consult with a compressed air professional to assist in your design or upgrades prior to writing any equipment specifications.

Compressor 1, Compressor 2, Compressor 3…You Get The Idea

April 5, 2016Ken Bean

With a room full of compressors, how do you keep them all playing together nicely? Central controls is the key to an energy efficient system with multiple compressor. Even with various types and brands a central control system can form a chain of command that keeps the plant satisfied while reducing energy costs.

The simplest central control is utilizing the existing compressor controllers for communication between the compressors allowing one or two units to focus as the lead machine and calling on the remaining compressors to assist in high load conditions. This could be by automatically loading or modulating one or several of the remaining units.

System master controls have many functional capabilities, including the ability to monitor and control all components in the system as well as trending data to enhance maintenance functions and minimize costs of operation.

What if your compressors are from multiple manufacturers and the controllers will not communicate with each other? Time to call on an outside source such as IZ Systems. The IZ Systems central control system can communicate with all compressor manufacturers controls and allow many enhanced functions not usually associated with normal compressor controls such as web based control, real time energy consumption and even contracts allowing our specialist to monitor your compressed air components for you remotely, giving you piece of mind 24/7/365.

Does the C-Suite Have Room For One More?

March 29, 2016Ken Bean

For over a decade I’ve been focusing on client education related to the true cost of compressed air. We’re all making progress but there are still those that fight the price tag on energy efficient systems. Instead, choosing the low initial investment route when the overall cost of ownership is primarily dictated by energy cost.

A recent article in the Harvard Business Review shared information about how much utility waste actually occurs in manufacturing. I felt the article had such impact that I’m choosing to take this weeks #TipTuesday post and simply direct you to read their article.

Considering that compressed air consumes a major portion of the utility budget there will always be savings opportunities related to the compressed air system. I’m always available to assist you in your search for a more energy efficient system.

I hope this article arms you with valuable information in your efforts to become a more energy conscience consumer while boosting your profit margin at the same time.

The full article can be viewed at http://bit.ly/1RFY1Z8

Contact me to discuss a compressed air energy audit.

Control Your Compressed Air

March 22, 2016Ken Bean

Compressed Air Controls

Improving and maintaining compressed air system performance requires not only addressing individual components, but also analyzing both the supply and demand sides of the system and how they interact, especially during periods of peak demand. This practice is often referred to as taking a systems approach because the focus is shifted away from components to total system performance.

Latest edition controllers from both the OEM and aftermarket suppliers offer the most sophisticated algorithms for unit control and incorporate sensitive digital sensing devices which all combine to give you the most efficient and reliable control. The better control you have of your compressor allows operators to select the lowest possible operating pressure allowing the plant to save significant money on operations and maintenance costs. Almost all of these controllers offer remote monitoring and remote control where operators are not required to be standing by in the compressor area to monitor data points or select update operating methods.

Controls from IZ Systems offer a complete compressor control automation package capable of handling any type of compressor, dryer, cooling tower or chiller system. Thus allowing integrated control of the entire system which further reduces the operations cost and further improves reliability.

Should I Use Compressed Air?

March 15, 2016March 15, 2016Ken Bean

Decisions, Decisions!

Last month I posted an article discussing the options of using compressed air vs. electric. There were several questions regarding cost calculations.

As a follow up, Todays post will discuss compressed air cost calculations to determine if compressed air should be used for specific applications.

This allows you to determine if compressed air should be used in specific applications (ie. as fans or blowers), or if other electric-motor operated equipment would be more efficient.

First calculate the volume of air produced annually for a specific operation by multiplying:

horsepower (hp)

cubic feet per minute per horsepower (cfm/hp)

total operating hours per year (hr/yr)

60 minutes per hour (60 min/hr)

% time fully loaded

% full-load horsepower

Volume of air produced annually

Then calculate the cost per 1,000 cubic feet (cf) by dividing the total energy cost to operate the air compressor by the volume of air produced annually, then multiply by 1,000. Cost per year / Volume of air products * 1000 cf

Example Calculations

The following example represents a typical small job-shop manufacturer.

A facility operates a 100 hp air compressor 4,160 hours annually. It runs fully loaded, at 94.5 percent efficiency, 85 percent of the time. It runs unloaded at 25 percent of full load at 90 percent efficiency, 15 percent of the time. The electric rate is $0.06 per kWh, including energy and demand costs. The cost per year to power the air compressor will be as follows.

Fully Loaded

Unloaded

The total annual energy cost to operate the air compressor is $17,524. The following calculation shows how much it will cost to use compressed air to operate a specific end use. Assume 3.6 cfm per horsepower and that this rate applies when the compressor is fully loaded.

Volume of air produced annually Cost per 1,000cf ($17,524 / 76,377,600) * 1000 = $0.23

Over the life of a compressor, energy costs will be five to 10 times the compressor’s purchase cost. Energy savings can rapidly recover the extra capital required to purchase an energy-efficient air compressor .

A 1.17 rated horsepower air operated mixer uses 45 cfm at 80 pounds-per-square-inch (psi) and operates 40 hours per week. The cost of the compressed air to operate this motor over a year is $1,292. A comparably sized electric motor of Energy Policy Act (EPACT) efficiency, rated for hazardous locations, is around $350. The cost to operate the EPACT motor under the same conditions is less than $100 per year. Including installation, payback is under one year.

Pressure Fluctuation

March 8, 2016Ken Bean

So there are locations in your compressed air system that the pressure just seems to fluctuate? With the maze of pipes, you have to consider pressure drop for certain areas. Most clients compensate for low or fluctuating pressures with a common fix: Raise the compressor output pressure. While this will usually solve the low pressure problem it rarely solves fluctuation and in addition it also increases your cost of power to produce higher pressure air. The input power for a compressor increases 1% for every 2 PSIG in pressure elevation! So what’s a plant to do?

Pressure/Flow Controllers

Pressure/Flow Controllers (P/FC) are system pressure controls that can be used in conjunction with the individual and multiple compressors. A P/FC does not directly control a compressor and is generally not part of compressor package. A P/FC is a device that serves to separate the supply side of a compressor system from the demand side, and requires the use of storage. Controlled storage can be used to address intermittent loads, which can affect system pressure and reliability. The goal is to deliver compressed air at the lowest stable pressure to the main plant distribution system and to support transient events as much as possible with stored compressed air. In general, a highly variable demand load will require a more sophisticated control strategy to maintain stable system pressure than a consistent, steady demand load.

“Credit to the US DOE for the preceding paragraph”

Contact a compressed air professional to discuss your particular low or fluctuating pressure concerns.

Can Your Air Compressor Make Phone Calls

March 1, 2016August 3, 2016Ken Bean

I read an article (link below) Sunday night from “Plant Services” discussing how the IIoT is coming to compressed air. If you’re not familiar with IIoT, it’s the industrial version of the IoT. In case you’ve not heard of IoT, let me give you a quick explanation. IoT stands for the “Internet of Things” and subsequently, IIoT stands for the “Industrial Internet of Things”.

The premise of IoT is that you and your entire home can be connected with all the components and subsystems being able to communicate and interact with each other. Basically, a Smart Home. What drives me crazy is that the authors of these articles promote this is new. This is NOT NEW! My house has been automated for over 20 years. The lighting, HVAC, security system, garage doors, home theater, whole house sound system along with others all respond to the central computer that controls it all and can be activated by buttons on my iPhone, keypads in the house or timed based controls. It doesn’t need access to the internet, nor do I want it connected to the internet. One less thing I have to be concerned with related to viruses and hacking. Sure a connection to the internet could add a few features to my system but it’s not worth the worry at this point.

Now on the article in “Plant Services” discussing IIoT and how its coming to compressed air equipment. It states how compressed air equipment utilizing IIoT and connecting to the internet will be “a game changer based on the energy-saving impact”. It further states “it will bring smarter control for better efficiency and easier compliance reporting”. My question is: compliance to what and reporting to who?

The goal of any compressed air system in today’s world is better efficiency but you certainly do not need an internet connection for that to happen. My vendor for central compressed air system control (IZ Systems) has been providing this capability for years. Maybe not as long as my house has been automated but for a lot of years. The current system doesn’t require changes to the local controls and can be tied into nearly any type or brand of compressed air equipment. Thus making the system reliable as any failure in the central system will revert control back to the local controller.

The key to energy efficiency has nothing to do with the internet but rather with the central processor that controls the compressed air equipment while monitoring the entire compressed air system and more importantly, the proprietary algorithm that resides in the central processor. Yes, they can use an internet connection to remotely monitor the system but this plays no part in the efficiency and in fact, many of my existing clients will not allow their equipment to access an internet connection due to the same concerns I have over my house. Additional security concerns. The benefits just don’t outweigh the potential headaches.

But, the article states, with the IIoT, my compressor can call the service technician if there is a potential problem. I’m sure this would save all my clients some time however most of my clients already tie equipment monitoring into their DCS and trend various data points such as temperature, pressure and vibration. If there is an escalating problem the DCS notifies them and they determine who needs to be called for further inspection or repair. So in my opinion, having your air compressor make phone calls is not going to add a lot of hours to your day.

Rather than waiting and hoping the IIoT progresses to a usable point, in my opinion, your money would be better spent investing today in a solid service contract with a company that can provide true vibration analysis. I’m not talking about trending but rather vibration analysis by professionals that know what the frequency’s should be on your equipment and can spot problems from one initial vibration analysis.

I think you can determine that I’m no luddite. In fact, quite the opposite. I love technology and the great things it can provide us. I just don’t want my clients getting caught up in the wave of hype surrounding a supposed new technology and spending money on features that are either easily available today or worse, for something they don’t really need.

Perhaps as the IIoT progresses I’ll be proven wrong and this technology can truly provide value to my clients. But for today, I see it as a half baked cookie that nobody really needs to bite into.

Here is a link to the original article if you’re interested.

Desiccant Dryer Control

February 21, 2016Ken Bean

Desiccant air dryers utilize a tremendous amount of energy through the consumption of compressed air and/or heat to regenerate the desiccant bed.

The use of hygrometers or dew point meters is commonly applied to reduce the amount of energy usage.

A recent article by “Compressed Air Best Practices” informs end users that this type of control is not the panacea that manufacturers would have you believe.

Seeing is not always believing

However, the use of an in (desiccant) bed capacitance probe can assure a lifetime of proper operation with no calibration required. The AMLOC capacitance probe used exclusively on dryers manufactured by Pneumatic Products Corporation (PPC)

AMLOC®

The AMLOC Energy Management Systems maintain accuracy, dew point stability and never need recalibration. Patented one quarter century ago, AMLOC® generates tens-of-thousands of dollars in energy saving annuities for industry leaders. The model of durability, THE PTFE or ceramic coated, stainless steel capacitance probes sense the changes to the dielectric constant imparted upon the desiccant by the extracted water vapor. Capable of identifying an aging or fouled bed, desiccant regeneration cycles are managed with precision.

Air or Electric

February 16, 2016Ken Bean

Air Audits can discover a multitude of energy saving ideas in your plant.