Compressed Air System Testing in Food Industry ...

Compressed air is the food and beverage industry’s “fourth utility” after the big three of water, electricity, and natural gas. The reliability of this fourth utility depends on predictable air pressure, which means even small leaks can come at a high price.

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Here’s a look at air leaks commonly found in the food and beverage industry, along with best practices and technologies to address them.

The Fluke ii900 Industrial Acoustic Imager includes technology that adds a visual component to traditional compressed air leak detection best practices for easier detection and fixing of air leaks.

Food and beverage manufacturers have unique considerations when it comes to compressed air leaks because product consistency is critical to brand reputation and compliance, especially since production plants and equipment are subject to strict controls and regulations to avoid contamination.

In food and beverage plants, multiple air compressor assets connect through pipes to deliver compressed air to move product, operate pneumatic tools or pump liquids for a variety of purposes in production chains, packaging, and cleaning. Here are some examples:

• Snacks and nitrogen air cushioning: Nitrogen flushing is used to fill bags to air cushion delicate snacks to prevent damage. Oxygen is excluded for use because it reacts with food products, especially those made with oils.
• Food and cleanliness: Compressed air is purified and filtered to ensure food safety and to maintain the proper pressure dewpoint needed to prevent microbial growth.
• Fruit and vegetable peeling: In preparation for packaging, pressurized air jets efficiently remove peels from fruits and vegetables. High-pressure compressed air is also used to cut foods as a cleaner alternative to knives or blades.
• Breweries, fermentation, and bottling: Compressed air increases oxygen levels to complete the bacterial fermentation process. Air compressors reduce residual oxygen during bottling and bottles are flushed with carbon dioxide and filled with beer using pneumatically powered machinery. Because breweries operate in warm environments, systems are more vulnerable to leaks.

Air leaks at any point can slow down production, affect product quality, create safety or contamination problems, or all four — and damage the bottom line.

The hidden costs of compressed air leaks

Compressed air and gases need to be available at a specified pressure to achieve production and quality targets, yet many facilities accept air leaks as a cost of doing business. Those costs can be high in energy loss but often in other hidden ways such as efficiency, quality and downtime.

According to the Compressed Air & Gas Handbook Seventh Edition published by the Compressed Air & Gas Institute (CAGI), “A single ¼-inch leak in a compressed air line can cost a facility from $2,500 to more than $8,000 per year. Locating and fixing leaks will result in significant savings depending on pressure requirements and energy costs.”

Benefits of compressed air system testing

• Increase efficiency through regular maintenance: Compressed air systems not regularly maintained after installation could lose 20 to 30 percent of compressed air in leaks alone.
• Reduce expense: Pressure drop is often misdiagnosed as equipment failures, resulting in additional capital investment in new air compressors.
• Decrease downtime: Lost production time from pressure drops or installing new equipment will require equipment downtime and negatively impact planning schedules. Unplanned downtime costs an average of $200 per minute making it critical to avoid.
• Improve product quality: Insufficient pressure results in defective package sealing or the edible product not meeting consistent texture or flavor requirements.
• Improve product safety: Leaks that cause contamination lead to high costs from waste, compliance penalties and reputational damage.
• Decrease carbon footprint: Systems with air and gas leaks become inefficient, which impacts a company’s carbon footprint and prevents them from meeting sustainability or environmental targets.

The formula used to determine the extent of compressed air leaks at a facility is: Leakage (%) = (T x 100) ÷ (T + t) T = onload time (minutes), t = offload time (minutes).

If the compressed air system is configured with start/stop controls, start your air compressor when there is no system demand — after hours or off-shift. Then take several readings of compressor cycles to determine the average time to unload the system.

Air leak detection and correction methods

The first step in controlling processing and costs is to find air leaks at their point of origin. Here’s a list of common leak points:

• Condensate traps
• Couplings
• Fittings
• Flanges
• FRLs (filter, regulator, lubricator combinations)
• Hoses
• Packings
• Pneumatic holding tanks
• Quick disconnects
• Threaded pipe joints
• Tubes
• Valves

Air leaks are a big issue because they’re abundant and hard to find. Once found and fixed, more leaks tend to pop up due to normal wear and tear on the system.

While it may not be possible to eliminate every single leak, it is possible to reduce the total number with focused inspection using traditional detection methods. With these methods, once a leak is located, a paper tag is used to mark the spot. Four traditional detection methods include:

1. Sound: Hissing indicates leaks, which means the leak is sizeable since only a sound level greater than 60 dBA is audible without leak detection equipment. Since most plants are noisy and often require worker ear protection, listening for leaks must occur during downtime — between shifts, on weekends, or during scheduled maintenance.
2. Water and soap: Technicians spray soapy water on areas of audible leaks, and where bubbles appear is the leak spot. The method is protracted, far from precise, and requires cleanup since soapy water overspray creates a slipping hazard. In some clean and contamination-protected processes it is not allowed.
3. Ultrasonic acoustic detection: During downtime, technicians wearing earphones scan potential leak spots with a parabolic-dish or cone-shaped accessory. When a leak-indicating noise is detected, the technician switches to a wand-shaped device that must be held a couple of inches from the leak to pinpoint the exact location.
4. Using outside experts: Engineers or other experts are engaged usually once a year to save money and disruption. They use one or all the traditional techniques, and repairs and checks handled by in-house technicians.

None of these methods is foolproof and most require downtime, which leads to lost time and money.

Compressed air leak testing helps coffee roaster easily identify energy savings of 10%

Project engineers at a coffee roasting company participated in a pilot study using industrial acoustic imaging technology in a facility where conditions tend to generate many leaks. The test identified the company could save more than 10% per year in energy consumption with the new leak detection device.

The 300,000-square-foot facility houses a coffee roasting and packaging area, coffee wet process area, and tea blending and packaging area. All operations require proper air pressure to efficiently complete processes and traditional leak detection methods couldn’t keep up.

On an average day, the facility uses from 1,000 to 1,600 cubic feet per minute (cu. ft/min) of compressed air. The company’s compressed air system, which consists of five air compressors totaling 585 horsepower, powers automation and tubing used to feed the operation’s nitrogen generation system. Nitrogen is used to improve the quality of coffee. Additionally, the inert gas is used for blending of tea.

With the Fluke ii900 acoustic imaging camera, the team identified potential energy savings of 10%, which is in keeping with its goal of improved sustainability. The new approach also showed how the team could simplify the air leak detection process, allowing the project engineers to keep staff working on products rather than stopping for long periods to detect and fix air leaks.

In a pilot test, a coffee roaster used the Fluke Industrial Acoustic Imager to easily identify and tag as many as 52 air leaks, including leaks in many difficult locations.

See air leaks for the first time with an acoustic imaging camera

An advancement in leak detection technology in the form of a portable acoustic industrial imager is making it easier to detect leaks and avoid lost profits.

The Fluke ii900 air leak detector allows users to locate and view air leaks on an LED screen in real time with a point-and-shoot process that doesn’t require a specialized technician. Most users can get up to speed in about 10 minutes. Technicians can also work quickly from a safe distance while equipment is running. Additionally, the device makes it easier to find leaks in hard-to-reach spots or to distinguish between multiple leaks within the same area.

The hand-held imager contains an array of ultra-sensitive microphones that detect sounds in both the human hearing and ultrasonic ranges for sound and then present them visually. The device then applies proprietary algorithms to the results and instantly produces a visual map of the leak on screen. The image of the leak is layered over a visible-light image of the area so operators can quickly pinpoint the leak location.

The Fluke ii900 Industrial Acoustic Imager scans areas up to 50 meters in normal industrial conditions.

The Fluke ii900 can also be used to verify successful repairs. If there’s a question, scans captured as stills or live videos can be shared and discussed with colleagues. The captured images eliminate the need to climb ladders or mark the leak with the usual fragile physical tag.

How to reduce the costs of hidden air leaks

Using common or new detection methods, there’s no time like now to remove the hidden costs and unnecessary waste of air leaks. Here are some best practices to follow:

• Take a systems approach: Often fixing a leak will increase system pressure, making smaller leaks larger, affecting the entire system. Combine changes with overall strategies for improved energy use and more robust control systems. Although they may be challenging to make, capital purchases often yield energy savings that substantially reduce payback time.
• Audit frequently: Frequent auditing—more often than the typical yearly or quarterly leak inspections—saves time, money, and resources over the long run, even if you need to shut down equipment. New imaging technology means you can zero in on leaks and fix them on an ongoing basis without losing valuable production time.
• Confirm root causes of pressure drops: Pressure drop can be misdiagnosed as equipment failure. Before making capital expenditures, leak checks and fixes may save thousands or hundreds of thousands of dollars and help instantly regain capacity.
• Log and track and verify over time: It’s important to record exactly where leaks have occurred since these weak spots tend to be where new leaks will happen and inspect those areas regularly. Logging information online allows data to be easily shared and used to impose discipline on the review process. Check soon after the repair is made to determine whether leaks have either been eliminated or need further attention.

Choosing the right compressor

Buying a quality air compressor that’s best suited to your needs will save you time and money in the long run and it’s an easy process that just requires understanding a few key concepts. This guide will help direct you towards making the best possible purchase.

Selecting the right compressor will mainly depend on four factors:

• The total air consumption of the all the tools you want to power simultaneously with the compressor.
• The recommended operating pressure of your tools.
• How you will use your air tools - ie. will they be run continuously or intermittently.
• Where you will run the tools - do you need the unit to be portable and is electricity available on site.

Tool Air Consumption

A compressor needs to supply enough air flow, at the right pressure, for an air tool to work correctly. So the air tools you want to use will be a primary factor when choosing a compressor.

Air tools have a specification for air consumption, normally measured in litres per minute (l/min) or cubic feet per minute (cfm). They also have an operational pressure measured in bars (b) or pounds per square inch (psi).

An air saw for example may have an air consumption of 170 l/min (6cfm) and require a pressure of 6 bar (90psi) to operate correctly. You will need to consult a tools manual or manufacturer to determine the right air requirements for a particular tool.

Compressor - Free Air Delivery (FAD)

A compressor needs to produce enough air to meet the air consumption requirements of the tool(s) connected to it.

The volume of air a compressor produces is called the Free Air Delivery (FAD), also measured in litres per minute (or cfm). The FAD relates directly to a tool’s air consumption requirement.

For an air saw that has an air consumption of 170 l/min the compressors FAD rating will need to be at least 170 l/min.

If you intend to operate multiple tools at the same time you will need to add up the air consumption values of the tools and use a compressor with an FAD rating that meets the total air demand.

For example, to simultaneously run an air saw (170 l/min) and an air ratchet (113 l/min) you will need a compressor with an FAD of at least 283 l/min (170 + 113).

The FAD ratings for all compressors sold at Total Tools are determined according to the Australian Standard AS 4637 2006.

Air Pressure & Quality

A compressor also needs to deliver a volume of air at a tools operational pressure. If a tool requires 12 bar (174psi) to operate you need a compressor that can pressurise air to 12 bar.

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If a tool needs only 6 bar (90psi) a pressure regulator fitted to the compressor will allow you to adjust the air supply to a lower pressure.

Note: Excessively high pressure can damage tools not built to handle it.

Air Quality

Compressors can produce air of varying quality. Dust, moisture and oil particles can all be present in the air flow unless they are filtered out.

If your tools or application requires “clean” air consider a compressor with particle and moisture filters installed. Oil-less pumps are also available which negate the risk of oil entering the air fow.

Air Tool Specifications

This chart shows the approximate air consumption and operating pressures you can expect from common air tools.

Note: this chart is only a guide, your tools may differ so consult your manual or manufacturer to obtain correct specifcations.

Tool Usage

The third factor to consider when buying a compressor is how you intend to use your tools.

The volume of air a tool may require will be affected by how you use that tool. An air saw that’s run in continuous long bursts will require a greater volume of air to operate efficiently over that period than if it is run in intermittent short bursts.

Pressure Cycle

Most compressors force air into a storage tank, increasing the pressure until it reaches an upper pressure limit at which the compressor shuts off.

When the compressed air is being used by a tool the pressure decreases until the tank reaches it’s lower pressure limit, at that point the compressor turns on to re-pressurise the tank. This is the compressor pressure cycle.

Compressing air produces heat which can damage the compressor if it’s not managed. When the compressor turns off (after reaching maximum tank pressure) it has time to cool down while the air in the tank is being consumed.

When a tool consumes the stored air quickly the time for cool down is reduced because the unit needs to turn on to repressurise. If not enough time is dedicated to the cool down phase the compressor can overheat and become damaged.

Duty Cycle

The ratio between the pressurisation and cool down phases is called the Duty Cycle. Ideally to maximise a compressor’s operational life it’s duty cycle over any given timeframe should be no more than 60% of the time turned on and 40% turned off (cooling down).

If you think you’ll be using high air consumption tools in a continuous manner consider a compressor with a higher FAD rating and/or larger storage tank to reduce the risk of wearing out or overheating the unit.

Where do you want to use the compressor?

Where you need to operate your tools & compressor is the fourth major point to consider when buying a compressor.

Portability

Do you need your compressor to be portable? If you want to move your unit around easily then your compressor will be limited in size, power and volume of air that it can produce.

Electric vs Petrol Engine

A petrol compressor is best suited for outdoor applications where electrical power isn’t available. Never use one in an enclosed environment.

A compressor with an electric motor however will be cheaper to buy and operate and also require less maintenance.

If you choose an electric compressor ensure you have adequate power to operate it. 10amp, 15amp or even 3 phase electicity may be required by your compressor.

Tank Size

The size of tank you require will most likely be determined by how you will use your compressor and the tools attached to it.

A tool used intermittently in short bursts should only require a small tank as the air volume will not be used up quickly. But if your compressor needs to sustain long periods of usage a larger tank is recommended.

Keep in mind that a larger tank will affect portability.

Site Location

Ensure the location you wish to place the compressor is large enough to fit the unit and has adequate ventillation so it won’t overheat.

Large workshop systems

If you are planning on installing a large air system with more than five workstations or you require air for an industrial application you may require a screw compressor and/or a specialised airline and filtration configuration, so consult with a Total Tools staff member and they will provide the expert advice you require to build the right system for your needs.

Other things you should know

• The tank stores air, it doesn't generate it. A bigger tank doesn't mean more air, it means a longer cycle time.
• Too much pressure for your application wastes energy and can damage tools.
• If you have three phase power, buy a three phase compressor, they are more efficient and reliable.
• Extension leads reduce power to the motor so when possible use a longer air hose instead.
• If you need a long lead, consider a petrol compressor instead.
• Overheating is a major factor in compressor failure, ensure your unit has adequate ventilation and access for maintenance.
• Divide the FAD by 28.3 to convert to CFM.

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