Preventative Maintenance for Refrigeration Systems

Cooler Connection

Suggested Refrigeration Systems Preventative Maintenance

Refrigeration systems are critical in the foodservice industry. It is very important to provide maintenance on your cooling systems to help prevent them from clogging or breaking down, which could lead to spoiled food, rotten food, etc. The following guidelines are provided from Heatcraft’s Operation & Instruction Manual.   By following these preventive maintenance steps, it does not guarantee your unit will not break down. However, by taking care and maintaining your refrigeration systems your unit is less likely to have problems.

Preventive Maintenance

Unit Coolers

At every six month interval, or sooner if local conditions cause clogging or fouling of air passages through the finned surface, the following items should be checked.

1) Visually inspect unit

• Look for signs of corrosion on fins, cabinet, copper tubing and solder joints.

• Look for excessive or unusual vibration for fan blades or sheet metal panels when in operation. Identify fan cell(s) causing vibration and check motor and blade carefully.

• Look for oil stains on headers, return bends, and coil fins. Check any suspect areas with an electronic leak detector.

• Check drain pan to insure that drain is clear of debris, obstructions or ice buildup and is free draining.

2) Clean evaporator coil and blades

• Periodic cleaning can be accomplished by using a brush, pressurized water or a commercially available evaporator coil cleaner or mild detergent. Never use an acid based cleaner. Follow label directions for appropriate use. Be sure the product you use is approved for use in your particular application.

• Flush and rinse coil until no residue remains.

• Pay close attention to drain pan, drain line and trap.

3) Check the operation of all fans and ensure airflow is unobstructed

• Check that each fan rotates freely and quietly. Replace any fan motor that does not rotate smoothly or makes an unusual noise.

• Check all fan set screws and tighten if needed.

• Check all fan blades for signs of stress or wear. Replace any blades that are worn, cracked or bent.

• Verify that all fan motors are securely fastened to the motor rail.

• Lubricate motors if applicable.

4) Inspect electrical wiring and components

• Visually inspect all wiring for wear, kinks, bare areas and discoloration. Replace any wiring found to be damaged.

• Verify that all electrical and ground connections are secure, tighten if necessary.

• Check operation/calibration of all fan cycle and defrost controls when used.

• Look for abnormal accumulation of ice patterns and adjust defrost cycles accordingly

• Compare actual defrost heater amp draw against unit data plate.

• Visually inspect heaters to ensure even surface contact with the coil. If heaters have crept, decrease defrost termination temperature and be sure you have even coil frost patterns. Re-align heaters as needed.

• Check drain line heat tape for proper operation (supplied and installed by others).

5) Refrigeration Cycle

• Check unit cooler superheat and compare reading for your specific application

• Visually inspect coil for even distribution

Air Cooled Condensing Units

Quarterly

1) Visually inspect unit

• Look for signs of oil stains on interconnection piping and condenser coil. Pay close attention to areas around solder joints, building penetrations and pipe clamps. Check any suspect areas with an electronic leak detector. Repair any leaks found and add refrigerant as needed.

• Check condition of moisture indicator/sightglass in the sight glass if so equipped. Replace liquid line drier if there is indication of slight presence of moisture. Replace refrigerant, oil and drier if moisture concentration is indicated to be high.

• Check moisture indicator/sightglass for flash gas. If found check entire system for refrigerant leaks and add refrigerant as needed after repairing any leaks.

• Check compressor sightglass (if equipped) for proper oil level.

• Check condition of condenser. Look for accumulation of dirt and debris (clean as required).

• Check for unusual noise or vibration. Take corrective action as required.

• Inspect wiring for signs of wear or discoloration and repair if needed.

• Check and tighten all flare connections.

Semi-Annually

2) Repeat all quarterly inspection items.

3) Clean condenser coil and blades

• Periodic cleaning can be accomplished by using a brush, pressurized water and a commercially available foam coil cleaner. If foam cleaner is used, it should not be an acid based cleaner. Follow label directions for appropriate use.

• Rinse until no residue remains.

4) Check operation of condenser fans

• Check that each fan rotates freely and quietly. Replace any fan motor that does not rotate smoothly or makes excessive noise.

• Check all fan blade set screws and tighten as required.

• Check all fan blades for signs of cracks, wear or stress. Pay close attention to the hub and spider. Replace blades as required.

• Verify that all motors are mounted securely.

• Lubricate motors if applicable. Do not lubricate permanently sealed, ball bearing motors.

5) Inspect electrical wiring and components

• Verify that all electrical and ground connections are secure, tighten as required.

• Check condition of compressor and heater contactors. Look for discoloration and pitting. Replace as required.

• Check operation and calibration of all timers, relays pressure controls and safety controls.

• Clean electrical cabinet. Look for signs of moisture, dirt, debris, insects and wildlife. Take corrective action as required.

• Verify operation of crankcase heater by measuring amp draw.

6) Check refrigeration cycle

• Check suction, discharge and net oil pressure readings. If abnormal take appropriate action.

• Check operation of demand cooling, liquid injection or unloaders if so equipped.

• Check pressure drop across all filters and driers. Replace as required.

• Verify that superheat at the compressor conforms to specification. (30°F to 45°F)

• Check pressure and safety control settings and verify proper operation.

Annually

7) In addition to quarterly and semiannual maintenance checks, submit an oil sample for analysis

• Look for high concentrations of acid or moisture. Change oil and driers until test results read normal.

• Investigate source of high metal concentrations, which normally are due to abnormal bearing wear. Look for liquid refrigerant in the crankcase, low oil pressure or low superheat as a possible source.

8) Inspect suction accumulator (if equipped)

• If the accumulator is insulated remove insulation and inspect for leaks and corrosion.

• Pay close attention to all copper to steel brazed connections

• Wire brush all corroded areas and peeling paint.

• Apply an anticorrosion primer and paint as required. Re-insulate if applicable.

Air Cooled Condensers and Fluid Coolers

At every six month interval, or sooner if local conditions cause clogging or fouling of air passages through the finned surface, the following items should be checked.

1) Visually inspect unit

• Look for signs of corrosion on fins, cabinet, copper tubing and solder joints.

• Look for excessive or unusual vibration for fan blades or sheet metal panels when in operation. Identify fan cell(s) causing vibration and check motor and blade carefully.

• Look for oil stains on headers, return bends, and coil fins. Check any suspect areas with an electronic leak detector.

2) Clean condenser coil and blades

• Periodic cleaning can be accomplished by using brush, pressurized water or a commercially available coil cleaning foam. If a foam cleaner is used, it should not be an acid based cleaner. Follow label directions for appropriate use.

• Clear unnecessary trash and debris away from condenser.

3) Check the operation of all fans

• Check that each fan rotates freely and quietly. Replace any fan motor that does not rotate smoothly or makes an unusual noise.

• Check all fan set screws and tighten if needed.

• Check all fan blades for signs of stress or wear. Replace any blades that are worn, cracked or bent.

• Verify that all fan motors are securely fastened to the motor rail.

• Lubricate motors if applicable (most Heatcraft condenser motors are permanently sealed ball bearing type and do not require lubrication)

4) Inspect electrical wiring and components

• Visually inspect all wiring for wear, kinks, bare areas and discoloration. Replace any wiring found to be damaged.

• Verify that all electrical and ground connections are secure, tighten if necessary.

• Check operation/calibration of all fan cycle controls when used.

General Safety Information:

  1. Installation and maintenance to be performed only by qualified personnel who are familiar with this type of equipment.
  2. Some units are pressurized with dry air or inert gas. All units must be evacuated before charging the system with refrigeration.
  3. Make sure that all field wiring conforms to the requirements of the equipment and all applicable national and local lodes.
  4. Avoid contact with sharp edges and coil surfaces. They are a potential injury hazard.
  5. Make sure all power sources are disconnected before any service work is done on the units.

The above refrigeration Preventative Maintenance Tips are located starting on pages 38-39 of Heatcraft’s Installation and Operation Manual. More walk-in refrigeration customer service information is available on Heatcraft’s website at http://www.heatcraftrpd.com/.

Cooler Connection @ Cooler Connection | Foodservice Blog Walk-in Refrigerators Coolers FreezersPost written by: Cooler Connection

Reactor Containment That Could Self Repair

Los Alamos researchers report a surprising mechanism that allows nanocrystalline materials to self repair themselves after suffering radiation-induced damage. Nanocrystalline materials are those created from nanosized particles, in the Los Alamos research, copper particles. A single nanosized particle – called a grain – is the size of a virus or even smaller. Nanocrystalline materials consist of a mixture of grains and the interface between those grains, called grain boundaries.

Nuclear reactor design or particularly, the materials that go into them, is one of the key challenges in finding materials that can withstand an outrageously extreme environment. In addition to constant bombardment by radiation, reactor materials may be subjected to extremes in temperature, physical stress, and corrosive conditions. Exposure to high radiation alone produces significant damage down to the nanoscale.

Self Repairing Nuclear Reactor Material Stages. Click on the image for the largest view. The captions are included.

Radiation can cause individual atoms or groups of atoms to be jarred out of place. Each vagrant atom becomes known as an “interstitial” a term often seen without explanation. The empty space left behind by the displaced atom is known as a “vacancy” and we don’t want vacancies in the containment vessels.  Thus every interstitial created also creates one vacancy. As these defects of the interstitials and vacancies build up over time in a material, effects such as swelling, hardening or embrittlement can manifest in the material and lead to a catastrophic failure. Therefore, designing materials that can withstand radiation-induced damage is very important for improving the reliability, safety and lifespan of nuclear energy systems.

Because nanocrystalline materials contain a large fraction of grain boundaries that are thought to act as sinks that absorb and remove defects, scientists have expected that these materials should be more radiation tolerant than their larger-grain counterparts.  Meanwhile, the ability to predict the performance of nanocrystalline materials in extreme environments has been severely lacking because specific details of what occurs within solids are very complex and difficult to visualize.

The Los Alamos researchers have begun to use computer simulations to help explain some of those details.

In a paper published in Science the Los Alamos researchers describe the never-before-observed phenomenon of a “loading-unloading” effect at grain boundaries in nanocrystalline materials. This loading-unloading effect allows for effective self-healing of radiation-induced defects. Using three different computer simulation methods, the researchers looked at the interaction between defects and grain boundaries on time scales ranging from picoseconds to microseconds (one-trillionth of a second to one-millionth of a second).  The loading-unloading effect of grain boundaries might just be key to repairing irradiated metal while in place.

In the shorter timescales radiation-damaged materials underwent a “loading” process at the grain boundaries, in which the displaced interstitial atoms became trapped – or loaded – into the grain boundary. Under these conditions, the resulting number of accumulated vacancies in the bulk material occurred in amounts much greater than would have occurred in bulk materials in which a boundary didn’t exist. After trapping the interstitials, the grain boundary later “unloaded” the interstitials back into vacancies near the grain boundary. The process activity cancels both types of defects, so healing the material.

This unloading process was totally unexpected because grain boundaries traditionally have been regarded as places that accumulate interstitials, but not as places that release them. Although researchers found that some energy is required for this newly-discovered recombination method to operate, the amount of energy was much lower than the energies required to operate conventional mechanisms – providing an explanation and mechanism for enhanced self-healing of radiation-induced damage.

The new modeling systems of the “loading-unloading” role of grain boundaries helps explain previously observed counterintuitive behavior of irradiated nanocrystalline materials compared to their larger-grained counterparts. The insight provided by this work provides new avenues for further examination of the role of grain boundaries and engineered material interfaces in developing self-healing of radiation-induced defects. Such efforts could eventually assist or accelerate the design of highly radiation-tolerant materials for the next generation of nuclear energy applications.

The prospect that a containment vessel could self-repair as it’s bombarded is a fascinating idea.  There should be follow up to test the reality of the computer simulations and physical testing to see the tolerance levels and recovery rates in real time.  While many might assume that new reactor technologies would obviate the need for this development the reality might just take reactor lifetimes out much further.

We have a lot of actinides of an unpleasant nature to use, wear down and extract the energy within on the way to safe and utterly worthless waste.  Self-healing materials in the reactors and the containment vessels can only help get the energy out and a result that can satisfy nearly everyone.

The Los Alamos press release listed the researchers in a group near the end, leaving no idea what concepts came from whom.  But here they are: Xian-Ming Bai, Richard G. Hoagland and Blas P. Uberuaga of the Materials Science and Technology Division; Arthur F. Voter, of the Theoretical Division; and Michael Nastasi of the Materials Physics and Applications Division.  Thanks folks, work worth doing.


Go here to see the original: New Energy and Fuel

Interpersonal Skills: What are They and Why are They Important in Hvac?

The technical knowledge you learn in HVAC school will be vital to your career success in HVAC maintenance and repair. The most important qualities you can bring to your job are technical skills and the ability to complete tasks well. However, also important is your ability to develop your interpersonal skills. Without these skills, technical skills can only get you so far. Think of professional athletes. Even when they are the best quarterback or best hitter, if no one wants to play with them, they’re not going to see the degree of personal success that they might if they took the time to get along with other people. Career success is about finding a balance between technical and interpersonal skills.

So what are interpersonal skills? Interpersonal skill is the art of dealing with people. Between co-workers and clients, a great HVAC technician has the ability to communicate well with people and interact in a positive manner. When you go to technical school to learn about the finer points of the heating and air conditioning industry, you will also learn how to interact well with the people you meet throughout your professional career.

Interaction with customers
When you interact with customers, your attitude is the key to a successful business relationship. This doesn’t mean you have to be outgoing all the time in your work. This simply means that your customer should find you pleasant. The goal for interacting with clients is to keep them happy so they will continue their business with you in the future and recommend you to their friends and family when they are in need of an HVAC maintenance and repair technician. If you are irritable or inattentive to your clients, they will be much less likely to call you again for maintenance or repair in the future. Show your clients that you are doing your best and are interested in making sure that they are satisfied with your work. That extra bit of attention will go a long way with your clients. A smile won’t kill you either. Not all of us are born comedians, but a joke here and there will make your customers a lot more comfortable with you as well. It’s already a bit awkward for them to let a stranger in to their houses, so show them that you are there to help them.

When you talk with your clients, make sure you keep your promises to them. When you tell a customer that you will have a part you need to fix their HVAC unit in by the end of next week, make sure that you are able to keep that promise. If you can’t, call them and keep them in the loop as to what you are doing. Don’t let your clients feel neglected. Try not to make too many promises in your work though, especially when you are not sure if you can keep that commitment. As we all do when we get busy, the tendency to forget is always a possibility. Be honest and truthful with your clients, but don’t kill yourself trying to keep difficult promises to them, even if your customer is pushy.

Why a Facilities Management Approach to Commercial Roofing Repair and Preventive Maintenance Works Best

On one level the practice of facilities management is the constant prioritizing and reassessing of which necessary facility repairs warrant immediate budget expenditures.

A commercial roofing contractor needs to understand this to effectively maintain and repair a facility’s roofing system(s).

The contractor must help the facilities manager walk the fine line between major repairs of older roofing systems and the minor repairs of new roofing systems that could become major repairs if neglected.  The idea is to maintain the newer roofing system(s) while over time bringing the older system(s) into an acceptable level of repair and performance.  It is also important for the facilities manager to understand when it is time to replace an older roofing system.  Typically that time is when too much money is being spent on the repair of an older roofing system, while too little is being spent on the necessary maintenance of newer roofing systems to prolong their life cycle.

Eventually, every commercial roofing system must be replaced. But, with inspection, maintenance and repair, building owners can extend a roofing system’s life cycle to maximize their return on investment.

According to the National Roofing Contractors Association preventive maintenance adds 30%-100% service life to a commercial roofing system. That means repair costs could be triple the cost of a preventive maintenance program over the life cycle of a commercial roofing system.

Another facilities management factor to consider in maintaining roofing systems is energy management.  Wet insulation in a roofing system loses energy.  According to the Building Owners and Managers Institute, good maintenance practices and good energy management go hand in hand. Some of the highest rates of return on energy conservation are generated simply by performing maintenance.

The key element to an effective facility asset management process is having professionals inspect those assets on a regular basis. On a periodic schedule determined with the building owner or manager the following should be done;

* Inspect the entire roofing system including flashings, drains or gutters and leaders, masonry, etc.

* Document each inspection (roof plan, inspection forms, and photo documentation). Each technician should carry a digital camera to document noteworthy roof conditions. Digital photos can be included with inspection reports.

* Perform infrared testing as needed to provide thermal energy reports to identify moisture within a roof system

* Remove all debris, clean gutters, leaders and drains

* Make minor repairs at the time of inspection.

* Provide estimates for roof repairs (or replacement if necessary)

* Comply with and document compliance with the maintenance requirements of any roofing system manufacturer warranties in effect.

Physical rooftop inspections and color infrared camera surveys are the keys to the effective documentation and analysis of energy loss, roof repair and maintenance issues.

In addition to the information gathered during roof inspections, the importance of maintaining warranty, design, installer, as-built materials data, and repair history information should be emphasized.  Contractors will benefit from assisting in the compilation of this additional data.

If this process is followed, the repair, maintenance and energy conservation of commercial roofing systems will be as cost-effective as possible.  And with this process, facilities-manager clients know years in advance of when a roofing system will have to be replaced, and what its projected expense will be.

For more information, www.flagshiproofing.com

Mel Thompson is a commercial roofing consultant for Flagship Roofing and Sheet Metal Co., Inc. in southeastern Massachusetts
www.flagshiproofing.com