New Humidifier Servicing Guidelines Released By The Humidity Group

HEVAC HUMIDITY GROUP CODE OF BEST PRACTICE.

HEVAC Code of Best Practice for the design, installation and maintenance of humidification systems to reduce microbial contamination risk in cold water humidification, misting and fogging systems.

1. INTRODUCTION

This Code of Best Practice has been prepared by the members of HEVAC (Heating Ventilating and Air Conditioning Manufacturers Association) Humidity Group to give guidance to manufacturers, suppliers, installers and operators of humidification systems.

The purpose of the guidance is to ensure that the risk of harm from the proliferation of harmful microbes that exists in all systems that contain water is reduced through good design, installation and operation. In particular, this Code of Best Practice addresses the risk presented by Legionella pneumophila.

This Code of Best Practice should be read alongside the following guidance and regulations:-

The Water Fittings Regulations 1999

The Provision and Use of Work Equipment Regulations 1998

The Control of Legionella Bacteria in Water Systems Approved Code of Practice & Guidance 2001 (L8) (HSC)

TM13 2000 Minimising the Risk of Legionnaires Disease (CIBSE)

2. CODE OF BEST PRACTICE

a. Design

Members of HEVAC who are manufacturers or suppliers of cold-water humidifiers, foggers and misting systems, undertake to minimise the risk of harm from the proliferation of harmful microbes that exist in all water systems through good product design, installation and maintenance guidelines.

Good product design means the incorporation of systems that address the sources of microbial growth, namely:

- Water status (stagnancy and wet surfaces)
- Temperatures that promote growth (20...45°C)
- Source of nutrients (such as material which encourage the development of microbes, airborne nutrients and biofilms).

In particular, these elements need to be given particular consideration where people, whether they are members of staff, the public or maintenance personnel, are exposed to the risk of inhalation of aerosols by direct contact with the humidifier, fogger or misting system, or from splashing, or food or product contamination.

A well-designed system will reduce the opportunity for bacteria to multiply by:

- Ensuring the cleanliness of the water supply such as filtration and ultraviolet sterilization.
- Flushing systems that empty a humidifier after use to avoid stagnation.
- Purging systems that ensure that stagnancy is avoided within the humidifier during operation and in any potential dead-leg supplying the humidifier.
- Where there is an air/water interface, the filtration of air to prevent the ingress of materials that might provide a source of nutrients for microbes.
- Avoidance in the humidifier of sections that are partially wetted during operation and after use.
- Building systems failsafe, so that failure of a safety system does not expose the user to risk, or providing alarms to warn of failure where this is not feasible.

- Building in alarms to remind users that maintenance is required.

- Designing to minimise potential risks caused by incorrect installation (for example, by building in components rather than separate supply).

- Designing to minimise maintenance requirements, and they should necessitate specialist attention only when breakdown occurs

- Designing O&M Manuals, which clearly reflect any potential risk to health, created by poor installation or maintenance and clearly describe the construction, operation, water supply and other installation requirements, maintenance requirements and parts. This should include a formalized system risk assessment.

b. Water Supply

The water supply should be from a system which has been subjected to a risk analysis and sampling in accordance with current guidelines for the control and prevention of legionellosis, including HSC ACoP L8.

It should be of potable quality and should run at below 20°C within 2 minutes of turning on the supply.

Water should be taken straight off the incoming mains supply but where a tank is used, it must comply with the Water Regulations. Consideration should be given to avoid any supply that may become stagnant due to insufficient usage due, for example, to over sizing of the tank.

c. Water Treatment

Some humidifiers require water treatment for their good operation. However, even where this is not a requirement for the humidifier, consideration should be given to potential problems caused by water quality such as:

- Calcium carbonate, (which can increase the risk of the development of Legionella. Other problems include scaling of equipment and white spots on glass and other surfaces).

- Suspended solids (problems include shadowing of microbes from UV light, build up of sediment, possible nutrient for bacteria).

- Microbes (can cause slimes and biofilms and blockages as well as increasing the risk of Legionnaires' disease).

Methods of improving water quality for humidification systems include the following:

Reverse Osmosis (removes most dissolved solids and bacteria)

Water Softening (exchanges dissolved solids that cause scale such as calcium)
Filtration (removes suspended solids and organics)
Ultra Violet light (kills bacteria in all water and surfaces it irradiates)
Chemical addition such as Ozone and chlorine dioxide (kills bacteria but care should be given to ensure residual chemical will not cause problems)

Water treatment equipment should be subject to regular inspection and maintenance according to the manufacturers instructions and site Risk Assessment.

d. Installation

A risk assessment of the equipment to be supplied and the use to which it is being put should be undertaken before specifying the component parts of the system. Only competent individuals should carry out risk assessment.

Consideration should be given to the following installation issues:

- The equipment must be accessible for inspection, cleaning and water sampling.
- Multiple power supplies to the equipment should fail safe.
- Where systems have antibacterial systems fitted that are critical to the safe operation of the equipment these should fail safe.
- A failure warning alarm should alert the user of the equipment that there is a fault.

- Drains should be arranged to prevent reflux.
- It should be possible to check that antibacterial systems (such as UV), drain and stagnancy prevention systems are working without disassembly of the equipment.
- Temperatures above 20°C and dirty ambient conditions can greatly increase the risk of contamination. Although the application has had a risk assessment by the installer, should the on-site conditions differ greatly to what was perceived, the installer should communicate to the system provider and the user the need for a further risk assessment.
- Installers of humidification systems should ensure adequate training is provided to the user on how to operate the system safely. This should be through clear instruction manuals and training.
- Upon completion on an installation, the end user must be notified that they should conduct their own risk assessment of the system, which should be included in the site Water System Risk Assessment.

e. Service & Maintenance

Suppliers and installers of humidification systems should ensure as far as possible that users have suitable maintenance arrangements in place. This requirement should be confirmed in writing after the sale and, where a service contract has been taken out with the supplier or installation company, a written notice (see appendix for an example) should be sent to the user of the system to advise them that the current service contract is about to expire.

Users must be made fully aware of the requirements for service and maintenance and a suitably trained person be responsible for routine maintenance and water sampling.

Only competent persons, as defined in the HSE's Code of Practice, should be used to clean and disinfect humidification systems.

The frequency and type of maintenance required will be specified by the manufacturer or installer of the system and must take into account the safe working duration of the systems components such as UV lamps, filters, electrical components etc.

A recommended frequency of cleaning and disinfection of the system will be specified by the manufacturer in the O&M manual. This shall be reviewed by the end user of the equipment on the basis of a risk assessment of the situation of the system in use.

The maximum recommended period between cleaning and disinfection will be no more than six months. This should be subject to site risk assessment and regular water testing.

Systems that generate an aerosol must be tested for Legionella every six months. In certain applications, such as food retailers, it is recommended the same water is also tested forE.Coli and coliform bacteria.

Where systems do not incorporate some of the design features outlined above, or where ambient temperatures exceed 20°C, or where the risk of aerosol inhalation or infection is greater, more regular sampling will be required. These might be using Dipslides for TVC, or more frequent testing for Legionella.

Persons responsible for maintenance should record who the competent persons responsible for maintenance are, water sampling frequency, tests and results, routine maintenance, cleaning and disinfection dates and details, as per the HSC's Code of Practice L8.

f. Risk Assessment and Water Testing

Risk assessments and water sampling must only be carried out by suitably trained, competent individuals. Manufacturers and suppliers of humidifiers should ensure that relevant staff are competent to carry out risk assessments and water sampling, and that staff should not undertake such services unless they are competent. Records should be kept of training and evaluation of such staff.

Water should be sampled for Legionella bacteria at least every six months, preferably from the reservoir of the humidifier (if an ultrasonic system), or at a representative point in the humidifier otherwise.

Samples should be taken in accordance with the recommendations of the manufacturer of the test, or laboratory carrying out the test. Analysis of Legionella samples should be carried out by a UKAS accredited laboratory, which is part of the PHLS Legionella QAS scheme.

Where the presence of Legionella is indicated, a review of the control measures and risk assessment should be carried out and remedial actions, such as disinfection, might be required.

For food-related applications, testing for E.Coli should be carried out in the same way, or using the same method as above or by using other proprietary tests for E.Coli.

Dipslide sampling should be carried out in accordance with the manufacturer of the test's instructions and incubated for 2 days at 30°C. Where TVC exceeds 103CFU/ml, a review of the control measures and risk assessment should be carried out and remedial actions, such as disinfection, might be required.

Water samples should be taken from the water in the humidifier at the point where contamination is most likely to occur, or as close as possible. Where this is not practical, a sample might be taken just prior to the humidifier, but after any pre treatment equipment or filters.

3. FURTHER INFORMATION

Additional information on this topic can be obtained from members of the HEVAC Humidity Group. Contact details are available via 0118 940 3416.

Original Publication can be found here: FETA Website

Planned Preventive Maintenance - How Important Is It?

How Necessary Is Planned Preventative Maintenance?

Is Preventive Maintenance Necessary?

 Reliability Centered Maintenance has changed the way we think about Preventive Maintenance (PM). It has caused some to question whether it is even necessary to do preventive maintenance. The truth is most manufacturing facilities would benefit from a good preventive maintenance program. It would be especially beneficial for those plants that rely on breakdown or run-to-failure maintenance. But, a preventive maintenance program is potentially risky, so it must be administered and performed properly to be successful. This paper will examine both the benefits and risks of preventive maintenance and offer some ideas on how to make it successful. We will start with a definition of preventive maintenance.

What is Preventive Maintenance?

CAREL Cylinder - Replacement For Steam Humidifier

Preventive maintenance is planned maintenance of plant and equipment that is designed to improve equipment life and avoid any unplanned maintenance activity. PM includes painting, lubrication, cleaning, adjusting, and minor component replacement to extend the life of equipment and facilities. Its purpose is to minimize breakdowns and excessive depreciation. Neither equipment nor facilities should be allowed to go to the breaking point. In its simplest form, preventive maintenance can be compared to the service schedule for an automobile.

A bona fide preventive maintenance program should include:

1. Non-destructive testing
2. Periodic inspection
3. Preplanned maintenance activities
4. Maintenance to correct deficiencies found through testing or inspections.
5. The amount of preventive maintenance needed at a facility varies greatly. It can range from a walk through inspection of facilities and equipment noting deficiencies for later correction up to computers that actually shut down equipment after a certain number of hours or a certain number of units produced, etc.

 Steam Humidifier Servicing

Many reasons exist for establishing a PM program. Listed below are a few of these. Whenever any of these reasons are present, a PM program is likely needed.

Reasons for Preventive Maintenance

CAREL Humidifiers - Require Planned Servicing

1. Increased Automation
2. Business loss due to production delays
3. Reduction of insurance inventories
4. Production of a higher quality product
5. Just-in-time manufacturing
6. Reduction in equipment redundancies
7. Cell dependencies
8. Minimize energy consumption (5% less)
9. Need for a more organized, planned environment
10. Why Have a PM Program

The most important reason for a PM program is reduced costs as seen in these many ways:

- Reduced production downtime, resulting in fewer machine breakdowns.
- Better conservation of assets and increased life expectancy of assets, thereby eliminating premature replacement of machinery and equipment.
- Reduced overtime costs and more economical use of maintenance workers due to working on a scheduled basis instead of a crash basis to repair breakdowns.
- Timely, routine repairs circumvent fewer large-scale repairs.
- Reduced cost of repairs by reducing secondary failures. When parts fail in service, they usually damage other parts.
- Reduced product rejects, rework, and scrap due to better overall equipment condition.
- Identification of equipment with excessive maintenance costs, indicating the need for corrective maintenance, operator training, or replacement of obsolete equipment.
- Improved safety and quality conditions.
- If it cannot be shown that a preventive maintenance program will reduce costs, there is probably no good reason other than safety to have a PM program.

The Law of PM Programs:

There are many advantages for having a good preventive maintenance program. The advantages apply to every kind and size of plant. The law of PM programs is that the higher the value of plant assets and equipment per square foot of plant, the greater will be the return on a PM program. For instance, downtime in an automobile plant assembly line at one time cost £10,000 per minute. Relating this to lost production time an automobile manufacturer reported that the establishment of a PM program in their 16 assembly plants reduced downtime from 300 hours per year to 25 hours per year. With results such as this no well-managed plant can afford not to develop a PM program.[1]

Preventive Maintenance Program Risks

As mentioned in the beginning of this report, preventive maintenance does involve risk. The risk here refers to the potential for creating defects of various types while performing the PM task. In other words, human errors committed during the PM task and infant mortality of newly installed components eventually lead to additional failures of the equipment on which the PM was performed. Frequently, these failures occur very soon after the PM is performed. Typically, the following errors or damage occur during PM's and other types of maintenance outages.

- Damage to an adjacent equipment during a PM task.
- Damage to the equipment receiving the PM task to include such things as:
- Damage during the performance of an inspection, repair, adjustment, or installation of a replacement part.
- Installing material that is defective, incorrectly installing a replacement part, or incorrectly reassembling material.
- Reintroducing infant mortality by installing new parts or materials.
- Damage due to an error in reinstalling equipment into its original location.
- Especially disturbing about these types of errors is the fact that they go unnoticed - until they cause an unplanned shutdown. There is some published data that illustrates this point. It comes from the fossil-fuel power industry.

Inside HygroMatik Steam Humidifier

A review of the data from fossil-fueled power plants that examined the frequency and duration of forced outages after a planned or forced maintenance outage reinforces this concept. That data showed that of 3146 maintenance outages, 1772 of them occurred in less than one week after a maintenance outage. Clearly, this is pretty strong evidence that suggests that in 56% of the cases, unplanned maintenance outages were caused by errors committed during a recent maintenance outage.

Having performed and supervised many industrial PM's, I also support this concept. I can remember many instances where it would take days after a PM was performed to get everything back to normal. This was particularly true when many components that came in contact with the product being produced were replaced. I remember working with the quality people on many occasions to insure that every position on a multiple position machine was once again producing first quality product. Many times it required adjusting and/or replacing components that were adjusted or replaced on the PM.

How to Have a Successful PM Program

The key to a successful Preventive Maintenance (PM) program is scheduling and execution. Scheduling should be automated to the maximum extent possible. Priority should be given to preventive maintenance and a very aggressive program to monitor the schedule and ensure that the work is completed according to schedule should be in place.

Preventive Maintenance Execution:

Traditional preventive maintenance was based on the concept of the bathtub curve. That is, new parts went through three stages, an infant mortality stage, a fairly long run stage, and a wear-out stage. The PM concept was to replace these parts before they entered the wear-out phase. Unfortunately, Reliability Centered Maintenance based on research done by United Airlines and the rest of the aircraft industry showed that very few non-structural components exhibit bathtub curve characteristics. Their research showed that only about 11% of all components exhibit wear-out characteristics, but 72% of components do exhibit infant mortality characteristics. These same characteristics have been shown to apply in Department of Defense systems as well as power plant systems. It is very likely that they apply universally as well. Therefore, they should be taken into account when configuring preventive maintenance on industrial equipment.

In order to have a successful PM program, the message is clear. The PM should focus on cleaning, lubrication, and correcting deficiencies found through testing and inspections. When there is a need to adjust or replace components, it should be done by highly trained and motivated professionals. Predetermined parts replacement should be minimal and done only where statistical evidence clearly indicates wear-out characteristics. In the absence of data to support component replacement, an age exploration program or the collection of data for statistical analysis to determine when to replace components should be initiated. Borrowing from the Japanese, lubrication points should be clearly marked with bright red circles to ensure that lubrication tasks are not missed. Cleaning should be carried our to remove dust, dirt, and grime because these things mask defects that can cause unplanned maintenance outages.

Motivating Preventive Maintenance Workers:

A quality preventive maintenance program requires a highly motivated preventive maintenance crew. To provide proper motivation, the following activities are suggested:

- Establish inspection and preventive maintenance as a recognized, important part of the overall maintenance program.
- Assign competent, responsible people to the preventive maintenance program.
- Follow-up to assure quality performance and to show everyone that management does care.
- Provide training in precision maintenance practices and training in the right techniques and procedures for preventive maintenance on specific equipment.
- Set high standards.
- Publicize reduced costs with improved up-time and revenues, which are the result of effective preventive maintenance.
- In addition to explaining the importance of a good preventive maintenance program and the benefits that can be derived from it, training is probably the most effective motivational tool available to the maintenance supervisor. Maintenance and training professionals have estimated that a company should spend $1200 per year for training of supervisors and $1000 per year for each craftsperson. In fact, due to advances in technology, if the company has not provided any training for craftspeople in the past 18 months, their skills have become dated.

HygroMatik HeaterCompact

(Ed's note: Hiring a good PM company can save on costs and training time for the customer.  Steam humidifiers and generators will need a service call, replacement steam cylinders and O-riings to ensure proper functioning of the humidifier, and to reduce down time costs).

Conclusion It is possible to have a successful preventive maintenance program. From a cost reduction viewpoint it is essential, but it does entail risk. When the proper care is taken, the risks, however, can be minimized. In order to minimize risk, preventive maintenance has to be carefully planned and carried out by well-trained and motivated workers. The biggest benefits of a PM program occur through painting, lubrication, cleaning and adjusting, and minor component replacement to extend the life of equipment and facilities.

References

Original article can be found here: Maintenance World
E. T. Newbrough, Effective Maintenance Management, (New York: McGraw-Hill, 1967).

William C. Worsham, Reliability Center, Inc.

Temperature V Relative Humidity

Air contains a certain amount of water vapour and the amount any mass of air can contain depends on the temperature of that air: The warmer the air is, the more water it can hold. A low relative humidity (% rH) means that the air is dry and could hold a lot more moisture at that temperature.

For example, at 20˚C a cubic meter of air can hold a maximum of 18 grams of water and at 25˚C it can hold 22 grams of water. If the temperature is 25˚C and a cubic meter of air contains 22 grams of water, then the relative humidity is 100%. If it contains 11 grams of water, the relative humidity is 50%. If it contains 0 grams of water, relative humidity is 0%.

The relative humidity plays a large role in determining our comfort level. If the relative humidity is 100%, it means that water will not evaporate - the air is already saturated with moisture. Our bodies rely on the evaporation of moisture from our skin for cooling and the lower the relative humidity is the easier it is for moisture to evaporate, making us feel cooler.

You may have heard of the heat index. The chart below lists how hot a given temperature will feel to us in various relative/humidity levels.

If the relative humidity is 100%, we feel much hotter than the actual temperature indicates because our sweat does not evaporate at all. If the relative humidity is low, we feel cooler than the actual temperature because our sweat evaporates easily; we can also feel extremely dry.

Low humidity has at least three effects on human beings:

·         It dries out your skin and mucous membranes. If your home has low humidity, you will notice things like chapped lips, dry and itchy skin, and a dry sore throat when you wake up in the morning. (Low humidity also dries out plants and furniture.)

·         It increases static electricity.

·         It makes it seem colder than it actually is. In the summer, high humidity makes it seem warmer than it is because sweat cannot evaporate from your body. In the winter, low humidity has the opposite effect. If you take a look at the chart above, you'll see that if it is 21˚C inside your home and the humidity is 10%, it feels like it is 18˚C. Simply by bringing the humidity up to 70%, you can make it feel 3˚C warmer.

For best indoor comfort and health, a relative humidity of about 45% is ideal. At temperatures typically found indoors, this humidity level makes the air feels approximately what the temperature indicates, and your skin and lungs do not dry out and become irritated.

Most buildings cannot maintain this level of humidity without help. In the winter, relative humidity is often much lower than 45%, and in the summer it is sometimes higher.