If you don't find the answer to your question below, please get in touch on 01785 256976 or by email at info@hvds.co.uk

AIR HANDLING

AHU stands for Air Handling Unit and is part of an Heating, Ventilation and Air Conditioning (HVAC) system. AHUs are usually found in the roof void or basement of medium to large manufacturing plants and will serve a specified production area within the factory.

AHUs clean and distribute the air within the building, maintaining good Indoor Air Quality (IAQ). Air is taken from outside the building, cleaned by air filters in the AHU, heated/cooled/humidified (depending on requirements) and fed around the production area through ductwork. Most AHUs will take the dirty air out of rooms, through the AHU and this will be recirculated back into the atmosphere. 

See below a table showing the required filter application grades for the food industry. We are asking customers to increase their air filter grade in the light of coronavirus (COVID-19).

Table of filter application grades

This will depend very much on the process type/production volume in your specific production area. We would recommend a risk assessment to determine the required replacement frequency and to put in place a set schedule rather than relying on pressure drop. 

The recommended measures to help prevent the spread of coronavirus (COVID-19) throughout your building via your HVAC system are as follows:

  • Checking the condition of the air filter and upgrading the filter media to F7 – F9 grade
  • Changing air filters*
  • Conducting a cleanliness audit
  • Cleaning or disinfecting the HVAC system
  • Carrying out preventative maintenance
  • Checking air flow rates and controls and, if possible, increasing the outside air rates
  • Maintaining internal humidity in the range of 40 – 60% RH

* At HVDS, we recommend changing filters regularly and to a set schedule, rather than relying on final pressure.

For more information about HVAC and COVID-19, please read this article.

As air filters in an AHU collect dirt, the volume of air that can flow through them will be reduced. This causes a pressure drop across the filters, which is measured by a pressure sensor. The pressure drop reading can indicate when the air filters need changing.

Some companies insist there is an optimal time to replace air filters from an energy/ efficiency point of view. At HVDS, we know from experience that it is better to be preventative. We therefore recommend changing your air filters according to a set schedule rather than relying on pressure drop readings, which might not be picked up by busy on-site engineers. Furthermore, retailers will often state what this schedule should be.

In regard to air quality, the CODEX ALIMENTARIUS (Recommended International Code of Practice General Principles of Food Hygiene)  4.4.6 AIR QUALITY AND VENTILATION states:

Adequate means of natural or mechanical ventilation should be provided, in particular to:
- minimize air-borne contamination of food

- control ambient temperatures
- control odours
- control humidity
Ventilation systems should be designed and constructed so that air does not flow from contaminated areas to clean areas. 

The BRCGS Food Safety Issue 8, Understanding Air Quality Requirements and Air Filter Specification in Food Production, published in August 2019, outlines the global standards for air quality in food production. The Standard requires the development of an effective hazard analysis and critical control point (HACCP) programme based on the requirements of the Codex Alimentarius system.

An air change is how many times the air enters and exits a room from the HVAC system in one hour. The number of air changes required per hour depends on the size of the area, the number of staff working in the area, the equipment used and the processing activity. For this reason, every area must be individually risk assessed. HVDS provides a full risk assessment service. Contact us for more details. 

The EHEDG (European Hygienic Engineering and Design Group) states that a minimum air exchange rate of 5 per hour is suggested with 10 air changes per hour the general rule for high hygiene (zone H) food process environments.

To calculate the number of air changes in a room per hour, you measure the supply airflow into the room, multiply the CFM (cubic feet per minute) by 60 minutes per hour, then divide by the volume of the room (height x width x length) in cubic feet, as follows: 

CFM x 60 minutes
__________________

Volume of room

 

Air mapping traces the movement of air through a food factory to help understand the distribution of air - an essential for air hygiene management. The results of the air mapping help establish best practice for maintaining positive air pressure, movement, volume and temperature control within each production area. Air distribution requirements in high care areas will typically be different to air distribution requirements in low care areas. 

HVDS air filters conform to ISO 16890. ISO 16890 is the new standard for testing air filters and replaced BS EN 779:2012 from 30th June 2018. The technical specifications and testing of air filters is much better, as reported efficiency represent operating condition (real-life) performance more accurately than previously, and the air filter classification system (based in particulate matter efficiency or ePM) is clearer. Unlike previously, the same filter classifications are used globally.

The classification system reports a simpler percentage efficiency within 1 of 4 particle size ranges:

ePM1 Filter efficiency for particle size range 0.3-1 μm
ePM2.5 Filter efficiency for particle size range 0.3-2.5 μm
ePM10 Filter efficiency for particle size range 0.3-10.0 μm
ISO coarse Gravimetric filter arrestance for filters not able to achieve minimum 50%  effciency at ePM10

If an air filter is classified as ePM1 = 70%, the filter has been tested and is known to remove 70% of particles in the size range of 0.3-1 μm.

Yes, HVDS is an Environment Agency Registered Waste Carrier. After fitting your new air filters, our engineers will remove your old filters from site and dispose of them according to the Waste Duty of Care imposed under section 34 of the Environmental Protection Act 1990.  

 

There are typically two sets of filters in an AHU: Primary (or pre-filters) and secondary filters. The primary filters are usually pleated panel filters. The pleated design allows for a large surface area to catch more dust and can catch dust particles down to 4 or 5 microns. Secondary filters are typically synthetic bag filters and will catch finer particles of dust, pollen and bacteria. Some AHUs have a final filtration stage for certain applications, such asaseptic filling and other critical operations. For this final filtration stage, a HEPA filter can remove particles from the air down to at least 0.3 microns.

The British Retail Consortium (BRC), now called BRCGS, is a trade association for the UK food industry, covering food safety, packaging, retail, responsible sourcing etc. The BRCGS publishes global standards for best practices for these areas for food and manufacturing industries.

The latest guidelines for food safety are published in the BRCGS Food Safety Issue 8, published on 1st August 2018. The section which lays out the requirements for air handling in the food industry is entitled, “Understanding Air Quality Requirements and Air Filter Specifications in Food Production”. 

HVDS does not recommend using air filters containing glass fibre media in AHUs. Glass fibre bag filters are known to release fibres, which could get through the HVAC system and into food. Furthermore, glass fibre filter media has carcinogenic characteristics.

HVDS offers an air testing and monitoring service to assess your Indoor Air Quality (IAQ). We provide you with a detailed report with recommendations as to how you can improve your IAQ to meet production and audit requirements. Clean air is essential for your production processes and for employee health and wellbeing.

Control of temperature and humidity is needed to prevent or reduce the growth rate of some micro-organisms in manufacturing and storage areas.  This will need to be factored into the HVAC system design. To discuss ytour requirements further, contact HVDS here.

This depends on the operation but it is typically 85% recirculated air and 15% replenishment/exhaust air.

HEPA filters are used as a final stage of air filtration in air handling units in buildings that require a higher level of contamination control, such as hospitals, research laboratories, pharmaceutical manufacturing plants and certain food production facilities. HEPA (high efficiency particulate air) filters offer further protection from microbial contamination. Read more here

ISOEN14644-3 Jan 2006 is the standard to work to for HEPA filter testing, meeting the most stringent requirements in the food manufacturing industry. For a HEPA filter test, please contact us here.

Air filters can become a source of contamination if not replaced regularly. In addition, cleaning the ductwork and other elements of the HVAC system will minimise the risk of air filter becoming a source of contamination. 

DUST, MIST, SPRAY, FUME & OIL EXTRACTION

Local Exhaust Ventilation (LEV) is an engineering control system, which extracts airborne contaminants (dust/fume/mist/spray/vapour/gas) from the atmosphere before they can be breathed in, and protects workers' health.

Flour dust and other powdered ingredients can cause asthma when breathed in. It is therefore law to protect your workers from their harmful effects. For example, exposure to flour dust should be as far below the WEL of 10 mg/m3 as possible.The HSE lists the control measures you should put in place. Read more here. The EH40/2005 Workplace exposure Limits can be found here.

By law you must protect your workers from the health risks of welding fume, as all welding fume can cause lung cancer, asthma and other health conditions. Welding fume is governed by the Control of Substances Hazardous to Health (COSHH) Regulations. The HSE lists the control measures you should put in place. Read more here. The EH40/2005 Workplace exposure Limits can be found here.

Silica dust is a natural substance found in rocks, sand, clay, bricks and concrete. By law you must protect your workers from the health risks of silica dust, as silica dust can cause lung disease. Silica dust is governed by the Control of Substances Hazardous to Health (COSHH) Regulations. The HSE lists the control measures you should put in place. Read more here. The EH40/2005 Workplace exposure Limits can be found here

The air your employees breathe should be monitored to ensure it conforms to COSHH Workplace Exposure Limits (WELs). Dust is considered to be a substance hazardous to health if it is present at a concentration in air equal or greater than 10mg/m3 (for inhalable dust) or 4mg/m3 (for respirable dust)

HVDS provides an air monitoring service. Using specialist equiopment, we measure ther concentration of airborne contaminants in both the working environment and the individual worker's breathing zone. The samples we collect are laboratory tested. Following the test results, we provide you with a comprehensive 'Occupational Exposure to Substances' report. This includes recommendations on how you can improve air quality on site, in line with WELs.

In order to determine which type of LEV is suitable for your application, you need to specify processes, sources and degree of control required.  The HSE has published a comprehensive guide to Controlling Airborne Contaminants at Work, which outlines what you need to consider when looking for an LEV. Contact our dust extraction team at HVDS for a free site survey here.

As above, in order to determine which type of LEV is suitable for your application, you need to specify processes, sources and degree of control required.  The HSE has published a comprehensive guide to Controlling Airborne Contaminants at Work, which outlines what you need to consider when looking for an LEV. Contact our dust extraction team at HVDS for a free site survey here.

LEV systems should have a thorough examination and test at least every 14 months, according to CoSHH regulations. You must keep a record of all examination and testing for at least 5 years. This applies to all dust, fume, mist, oil and spray extraction units that you have on site. 

At HVDS, we recommend a 6-monthly service inspection and an annual LEV examination. Every customer has a log book, which lists all the checks they should be doing themselves inbetween a service inspection and an LEV examination. 

Following an LEV service inspection or examination, our customers receive a report and a quotation for any remedial works identified, if systems have failed. HVDS engineers would then retest the system and a final report would be issued. 

The EH40/2005 Workplace exposure Limits can be found here

Silica dust is a natural substance found in rocks, sand, clay, bricks and concrete. By law you must protect your workers from the health risks of silica dust, as silica dust can cause lung disease. Silica dust is governed by the Control of Substances Hazardous to Health (COSHH) Regulations. The HSE lists the control measures you should put in place. Read more here. The EH40/2005 Workplace exposure Limits can be found here

WELs stands for Workplace Exposure Limits. These limits are assigned by CoSHH (Control of Substances Hazardous to Health) to a large number of hazardous substances and must not be exceeded. More information here

"ATmosphere EXplosible" (ATEX) is a set of EU regulations designed to ensure that products used in an explosive environment are safe. An explosive environment will contain combustible dusts or flammable gas, vapour or mist.  

Yes, HVDS is an Environment Agency Registered Waste Carrier. After fitting your new LEV cartridge filters, our engineers will remove your old filters from site and dispose of them according to the Waste Duty of Care imposed under section 34 of the Environmental Protection Act 1990.

LEV test engineers must be P601 qualified. P601 is the British Occupational Hygiene Society (BOHS) Proficiency Qualification - 'Thorough Examination and Testing of Local Exhaust Ventilation Systems'. HVDS LEV test engineers hold at least this qualification.

All HVDS dust engineers are trained to the required standard for the work they carry out on your site. They hold BOHS qualifications (from P601 - W201). The work they complete for you complies with the HSE and HSG258.

LEV cartridge filter life expectancy will depend on a number of factors, including:

          - Type and amount of contaminate being extracted

          - Type of filter (panel, fine/coarse dust etc.)

          - The process generating the contaminate

          - How well maintained the system is

The main factor determining the lifespan of a dust filter cartridge is the amount of particulate being generated.

On average a pre-filter should last for 1 up to 3 months and a HEPA filter should last for up to 12 months.

To establish a cartridge filter change schedule for your business, get in touch here.

Accordng to the ATEX 99/92/EC directive, employers must classify areas into zones where hazardous explosive atmospheres may occur. The classification given to a particular zone, and its size and location, depends on the likelihood of an explosive atmosphere occurring and its persistence if it does. Examples of combustible dusts in the food industry include: flour, custard powder, instant coffee, sugar, dried milk, potato powder and soup powder. Equipment and systems intended for use in explosive atmospheres, such as explosion relief panels, must be ATEX certified. 

The CoSHH regulations state that LEV systems should be checked at least every 14 months and maintained to a suitable standard for their purpose (or more frequently depending on manufacturer guidelines). Our P601 qualified engineers will routinely examine and test all parts of your LEV and will carry out any remedials picked up on an examination to comply with the HSE and HSG258 guidelines to prevent mechanical parts failing and to maintain extract efficiency.

At HVDS, we supply the full range of dust spares, including LEV filter cartridges, filter socks and sleeves, pocket bags etc. All spares are available for next day delivery and installation can be provided by HVDS trained engineers. We also supply spare parts for all makes/models of dust/fume/oil/mist extraction equipment. See our dust spares page for more information.

Mechanical service inspection checks the LEV components and takes differential pressure readings, static pressure readings and a reading from the compressed air manifold to ensure the system is working effectively. An LEV examination covers all the above. However readings are taken from test points along the ductwork and from hoods to ensure the system is running as per design and that exposure to dust is being controlled .

HVDS recommends having a mechanical service inspection every 6 months.

Yes, HVDS provides training for in-house engineers on site. Contact us for more details. 

Yes we do. Commissioning means setting up and balancing the system to ensure it is controlling exposure to the system's original design. We will commission an LEV system we have install upon request or commission a system you may already have installed on site.

The Work Exposure Limits (WELs) determine the hazard and then capture and contaminant is based on HSG258 requirements.

HYGIENE, CLEANING & MAINTENANCE

According to the BRCGS Food Safety Issue 8, AHUs should be cleaned regularly (6-monthly at a minimum) to remove any build-up of loose debris etc. We advise our customers to put a regular set cleaning schedule in place to keep their AHUs clean and to maintain good Indoor Air Quality (IAQ). HVDS engineers clean AHUs to TR19 standards.

Grease, dust and other debris that builds up in ductwork, fryer and oven flues can present a major fire hazard and compromises the energy efficiency of your HVAC system. The frequency of ductwork, fryer and oven flue cleaning will depend very much on your processes and production volume. Contact HVDS here for a survey to establish your cleaning needs. HVDS engineers clean AHU ductwork, fryer and over flues to TR19 standards.

Along the length of most metal ductwork are access doors, which allow ease of cleaning and maintenance. Where you ductwork does not have access doors, our engineers can install them for you.

We recommend cleaning your LEV system on inspection where possible. We recommend that inspections are carried out every 6 months. However, if good housekeeping is practised on site, systems should remain in a reasonable condition.

The BRCGS guidelines on AHU cleaning and maintenance are contained in Section 6 of the BRCGS Food Safety Issue 8. The guidelines recommend that AHUs are cleaned regularly (6-monthly at a minimum) to remove any build-up of loose debris etc.

Click here for the HSE publication on cleaning and maintaining your LEV.

Without a proper cleanliness survey, it is difficult to establish the state of your system and ductwork internally. A system that is clogged with debris will reduce the energy efficiency of your system and this increase your running costs. Mould and bacteria in your system will compromise food safety and the air your staff breathe. Contact our Hygiene Team here for a full cleanliness survey.

Yes, fabric ducting is removed and then washed in industrial washing machines or hand cleaned to remove any traces of build-up.

Our ductwork cleaning techniques include mechanical cleaning, rotary brushing, compressed air jetting and traditional hand cleaning. Our BESA accredited engineers work in accordance with industry standards.

Ensure you have the correct capacity and grade of filters at each stage in your air handling unit, as set out in the BRCGS Food Safety Issue 8.

The BRCGS Food Safety Issue 8, Section 6, Maintenance, Condition and Hygiene Monitoring gives best practice with regard to maintenance and hygiene of your HVAC system and lists the areas you should routinely check. At HVDS. we recommend putting in place a regular maintenance and cleaning schedule to ensure audit compliance, minimise contamination, hygiene issues and equipment breakdown. Our engineers are BESA trained to TR19, BS EN 15780 and HTM 03 01 standards. We provide a full hygiene and maintenance service for HVAC and LEV systems, including ductwork repairs and maintenance and internal ductwork inspections via camera probe. Contact us for more details. 

FABRIC DUCTING

Fabric ducting is a more versatile and efficient alternative to metal ducting with distinct advantages for the food industry. As it is made of a flexible fabric, HVDS designers and installation engineers can tailor the layout of your air socks and placement and size of air distribution holes to your air flow and air distribution requirements to meet the needs of your specific production area.  

Because of its lightweight and flexible design, fabric ducting is faster and easier to install, maintain and clean. Air socks can be removed for cleaning.                                                                                                                                       

Fabric ducting is made of non-permeable, synthetic fabric, which will not promote growth of bacteria and is washable. Most air socks on the market are made from a cotton-based material. The disadvantage of cotton is that the air flowing through the material cannot be guided in any way past the machinery and processes happening directly below the air sock on the factory floor. Our non-permeable, synthetic air socks are manufactured with  air distribution holes (laser cut by software) that govern the air flow pattern, guiding it past certain processes and machinery below. 

HVDS fabric ducts (or air socks) are manufactured specifically for use in the food production and processing industry.

Fabric ducting is a more versatile and efficient alternative to metal ducting with distinct advantages for the food industry. As it is made of a flexible fabric, HVDS designers and installation engineers can tailor the layout of your air socks and placement of air distribution holes to your air flow and air distribution requirements to meet the needs of your specific production area.  

Because of its lightweight and flexible design, fabric ducting is faster and easier to install, maintain and clean. Air socks can be removed for cleaning.          

Yes we do. We design and install fabric ducting to the specific requirements of your production area. Our trained specialists would conduct a full survey so you know all the options available. We also maintain and clean fabric ducting to prevent contamination and increase the lifespan of your AHU system.

The best way to prevent condensation, mould and contaminants in fabric ducting is to have them cleaned regularly and to a set schedule. We recommend 6-monthly or annual cleaning, depending on usage. We also recommend scheduling your air sock cleaning for just after factory washdown to help prevent mould and bacteria taking hold in the increased humidity. 

One of the main advantages of fabric ducting is that the size (and quantity and placement) of air distribution holes can be tailored to the needs of your production area. The size, quantity and placement of air distribution holes is calculated by specially developed software.

Well-made fabric ducting should last for 15 - 20 years, depending on how well it is maintained and cleaned. We recommend putting a maintenance and cleaning schedule in place to prolong the lifespan of your fabric ducting.

We recommend 6-monthly or annual cleaning of your air socks, depending on usage. 

Our BESA trained, experienced hygiene team will take down your dirty fabric ducting, which will then be laundered in industrial washing machines or hand cleaned, to remove all trace of build-up.

In order to prevent disruption to production during air sock cleaning, we recommend having a spare set of air socks, which HVDS can supply and install.

Yes, fabric ducting is removed and then washed in industrial washing machines or hand cleaned to remove any traces of build-up.

Yes, HVDS will supply and install replacement fabric ducting during cleaning, in order to prevent disruption to your production process.

Our fabric ducting is available in a variety of colours to match your production area, including white, blue, green, yellow, red, orange, grey and black. 

Our fabric ducting can be supplied, on request, with a membrane system for heating/cooling mode options. An internal membrane lines the air sock internally and this can be moved (by a motor) to open either the top of bottom section of the diffuser. In cooling mode, the membrane seals off distribution holes in the bottom section of the air socks, allowing air to flow through the top section. In heating mode, the membrane is moved to seal off the distribution holes in the top section, and the air flows directly downwards. This optimises system operation and indoor comfort.

Yes you can. The air socks we supply are made from a non-permeable material. They are manufactured with air distribution holes (laser cut by software) that govern the air flow pattern The distribution holes can be configured in such a way as to mirror what is happening on the factory floor, so that the air flow can bypass the processes and machinery directly below the air socks, such as check weighers, flow wrappers, weight sensitive machinery, production machinery etc. Most air socks on the market are made from a cotton based material, which means the air flows through the material and cannot be guided in any way around/past what is happening below.

HVDS can conduct a full survey of your existing air socks to determine suitability of the material and construction and acceptability of the condition for your production area. Contact us here to book your survey.

Air sock is another word for fabric duct. The two words are used interchangeably.

Air socks are a more versatile and efficient alternative to metal ducting with distinct advantages for the food industry.

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