Equipment Design and Maintenance

Introduction

Equipment used in the dairy industry ranges from simple cheese moulds and forms to highly complicated pasteurizers and aseptic processing and packaging systems. Regardless of its sophistication, your equipment must be well designed and effectively maintained to:

  • keep it working properly
  • reduce the risk that it will fail during critical processing operations
  • prevent it from becoming a source of biological, physical or chemical contamination to dairy products

To make sure your equipment is well designed and maintained, written equipment design criteria and a preventive maintenance program should be developed.

Procedures

An equipment design and maintenance program should include:

  1. Equipment Design
  2. Installation
  3. Equipment Maintenance
  4. Calibration

1. Equipment Design

General Criteria
  • Any new piece of equipment should meet a particular need. For example, a table provides workspace area, a pasteurizer eliminates pathogens in the product; a filling machine packages the product; and a heating, ventilating and air conditioning (HVAC) system provides clean ambient air.
  • Whether you select new or used equipment, it should meet the following criteria for food safety:
    • The equipment should be easy to take apart to reach all the areas that need cleaning.
    • The equipment should be made of materials that are smooth, non-corrosive, non-absorbent, non-toxic and easy to clean (such as stainless steel).
    • Surfaces should not have any pitting, cracks, recesses, open seams, gaps, lap seams, protruding ledges, inside threads, bolt rivets or dead ends. Residues can build up in these areas, allowing micro-organisms to grow and possibly contaminate the product.
    • All welds on food contact surfaces should be smooth, without any internal roughness, burrs, etc.
    • There should not be any areas where moisture can build up due to:
      • condensation
      • product spills
      • cleaning chemicals or rinse water that doesn't drain completely
    • Any hollow areas where moisture can be trapped must be sealed or eliminated wherever possible. This includes frames and rollers.
    • All essential covers, doors, panels, etcetera should be in good condition and used during operations.
    • Hand contact surfaces such as push buttons, valve handles, switches and touch screens should be designed to prevent liquids from building up or getting into the equipment. These liquids include water, cleaning chemicals and product.
    • The equipment should be made of materials that will not deteriorate over time from being exposed to cleaning and sanitizing solutions or to the product itself.
    • Utensils used for handling the product or for cleaning should have surfaces that are smooth, non-corrosive, non-absorbent and non-toxic. They should not have any pitting, cracks, crevices or seams. They should not have wooden handles.
    • The equipment should be designed to protect the product from contamination during operation. For example, there may be protective shields, lids or covers on various parts of a filling machine to protect product and containers from any environmental contamination. Similarly, there may be fail-safe mechanisms on a pasteurizer to make sure only properly pasteurized product enters the filling operation.
    • Complex equipment should have manuals that explain how to operate it, take it apart, clean it and maintain it. These manuals should be readily available to employees. If necessary, they should be translated into languages your employees understand.
Design Criteria for Product Contact Air Systems
  • Product contact air systems are enclosed pressurized systems such as:
    • pneumatic conveyors
    • air blows
    • air dryers
    • product overrun
  • The systems for generating and delivering product contact air must not contaminate the product with micro-organisms or physical contaminants such as particles, condensates or oil.
  • To make sure the air is clean enough to come in contact with the product:
    • the air must come from a clean source (whether it is outside or inside the plant)
    • the air must pass through a filter before it reaches the compressor
    • the filter must be easy to reach so it can be examined, but it must also be protected from the weather, drainage and physical damage
    • the filter and housing must be properly sized and designed so that the filter is sealed tightly against the frame and gaskets
    • the system should be easy to clean
    • there should be sanitary check valves to prevent product from moving back up into the air lines
    • check valves, air blows and agitation equipment should be easy to take apart since they often require regular cleaning and sanitizing
    • the compressing equipment must be designed to prevent the air from becoming contaminated by moisture, lubricants or lubricant vapours. For example, the equipment should use oil-free filters and have moisture traps in the air lines downstream from the compressor to remove excess moisture from the system.
  • Make sure oils and lubricants used in the air compressors are acceptable for use in a food plant. Acceptable products may be listed in the Reference Listing of Accepted Construction, Packaging Materials and Non Food Chemical Products published by CFIA.
  • If products are not on the list, plant operators may seek assurance of their acceptability by obtaining either
    • a letter of non-objection from Health Canada, or
    • a letter of guarantee from the supplier of the products
  • For more information on the acceptability of products, visit CFIA's website.
Criteria for Minimizing Metal Contamination
  • Dairy products can be contaminated by metal from a variety of sources, including:
    • contaminated ingredients
    • poorly maintained or deteriorating equipment
    • inadequate cleaning of equipment following maintenance.
    • employees who do not follow good manufacturing procedures (GMPs)
  • There are several ways to minimize the risk of metal contamination, including:
    • buying ingredients only from known, reputable suppliers that meet your specifications
    • following GMPs such as not wearing clothing with pockets above the waist (to prevent items falling into the product), not wearing jewellery, and cleaning product-handling equipment after any maintenance
    • regularly checking equipment and maintaining it to make sure it works properly at all times (see the section on preventive maintenance below)
    • training employees to be aware of contamination risks
    • filtering the product (such as incoming raw milk)
    • installing magnets and metal detectors in product lines
  • Metal detectors are valuable tools for detecting metal contamination of products in certain operations such as cheese packaging. Metal detectors must meet the following design requirements:
    • They must be suitable for the specific product and stage of processing. For example, butter should be screened for metal contamination before it is packaged, since it is wrapped in aluminum foil.
    • They should be able to detect the type of metal that is most likely to contaminate your product (ferrous versus non-ferrous metal). Stainless steel (a ferrous metal) is the most common metal used in the dairy industry and may be more likely to cause problems. For example, products can become contaminated by ferrous metal fragments from grinding stainless steel parts such as poorly aligned agitators or pump impellers.
    • They must be installed, calibrated and maintained according to the manufacturer's specifications.
    • They must be operated according to the manufacturer's operating manual or instructions.

2. Installation

  • The equipment design and maintenance program should include a floor plan showing the location of all the major pieces of plant equipment.
  • Make sure the equipment is:
    • located in a position that creates efficient product workflow and does not lead to cross contamination
    • easy to reach, with enough room to operate, clean and sanitize
    • easy to access for maintenance and inspection
    • not located over a drain (if there is drainage from equipment, install drainage lines to divert liquids to a drain)
    • exhausted to the outside, if necessary, to prevent excess condensation in the production area (for example, install exhaust hoods over ricotta or ghee kettles)
  • Any monitoring devices should be located where the operator can read them easily and there is enough lighting to read them.
  • If the product is exposed to the plant environment (such as unwrapped cheese on cutting tables), protect it from possible sources of contamination such as dirt, debris or condensation/leaks from overhead lines.
How to Install Equipment
  • All food contact piping should be installed by qualified personnel. In the case of stainless steel welding it is particularly important to have installers with experience in sanitary welding of food processing equipment. Sanitary welding produces smooth, seamless stainless steel welds.
  • After the equipment has been installed, thoroughly clean and inspect it before using it. Make sure there are no residues or materials left over from the installation process (such as metal burrs, chemical residues, etc.) on any product contact surfaces.
  • If the equipment includes monitoring devices, calibrate them before using the equipment.
  • Some complex equipment systems may need to go through a complete validation process after installation to make sure they work according to the manufacturer's specifications. For example, an aseptic processor must be able to maintain aseptic conditions throughout processing.

3. Equipment Maintenance

Equipment always requires a certain level of maintenance. "Corrective maintenance" is maintenance that needs to be done immediately due to a breakdown. "Preventive maintenance" is routinely scheduled maintenance that increases the life of the equipment and avoids breakdowns. Your written program should cover both types of maintenance.

Corrective Maintenance (CM)
  • From time to time, there will be equipment breakdowns that must be dealt with immediately without putting product at risk. Your corrective maintenance program should cover the following points:
    • If possible, remove all product from the equipment before beginning the repairs. If this is not possible, protect the product during the repairs and then discard any contaminated product.
    • Make sure the people doing the repairs are qualified to do the work.
    • Make sure the people doing the repairs follow GMPs to avoid contaminating the equipment or the product.
    • Make sure they avoid practices that could lead to product contamination. This includes:
      • using too much lubricant
      • not securely fastening all nuts, bolts and screws
      • using tools in finished product work areas that were also used on equipment that handles raw product
      • not re-installing protective covers
      • leaving tools lying about the equipment
    • Have a list of equipment suppliers with emergency contact information.
    • When doing repairs, use parts and procedures recommended by the manufacturer.
    • Even in emergency situations, avoid shortcuts or temporary fixes that could affect product safety. For example, don't use tape or vice grips since they cannot be cleaned and are a source of contamination.
    • Clean and sanitize tools before using them on food contact surfaces.
    • Make sure the people doing the repairs leave a detailed record (in a work order or log book, for example). It should include:
      • the reason for the repair
      • the actual repairs that were done
      • the time and date of the repairs
      • whether or not there was product in the equipment
      • how long the repair took
      • the repair person's signature
      • a list of any parts that were replaced and what was done with the old parts
    • After the repairs are finished, properly clean and sanitize the equipment before product is re-introduced to the equipment.
Preventive Maintenance
  • Preventive maintenance (PM) is the planned maintenance of equipment in order to:
    • reduce the risk of breakdowns
    • reduce the amount of corrective maintenance that needs to be done
    • make sure the equipment that can affect food safety is working properly and not leading to contamination of product
    • reduce the risk of physical or chemical hazards contaminating the product
  • It includes servicing equipment based on the manufacturer's recommended schedule or based on the operating conditions. Common tasks include:
    • inspections
    • lubrication
    • adjustments
    • testing
    • replacing worn or aging components to extend the life of equipment
  • Your PM program should include:
    • a list of people (employees or outside service companies) qualified to maintain each item of equipment
    • a list of all equipment that can affect food safety and requires regular maintenance
    • a specific program for pipeline gaskets and air systems
    • the tools to do the required maintenance tasks
    • a PM schedule for each piece of equipment
    • a method to make sure the scheduled work gets done and documented
Outside service personnel
  • Outside service personnel need to:
    • sign in and out when visiting the plant
    • understand and follow the plant's GMPs
  • If your plant has specialized equipment serviced by an outside company, keep the company's contact information readily available and up-to-date.
A list of all equipment that can affect food safety and requires regular maintenance
  • Keep a current list of all equipment that affects food safety, either directly (such as a pasteurizer or filler) or indirectly (such as a ventilation system or cooling system).
  • Have a floor plan that shows the location of each piece of equipment and how to access it.
  • Keep an inventory of parts that are essential to operate and maintain that equipment (such as gaskets, lubricants, filters and parts that often wear out).
A specific PM program for pipeline gaskets and air systems

Pipeline Gaskets

  • Most dairies have pipelines for moving product and cleaning solutions throughout the plant. These pipelines are constructed of pipe segments joined together with gaskets.
  • If gaskets deteriorate, product can leak out or air can leak into the pipeline. In either case, contamination can occur. Leaks of hot chemicals during cleaning and sanitizing can also pose safety risks to employees.
  • Replace all gaskets on a set schedule.
  • Monitor the condition of gaskets regularly and replace those that start to deteriorate. Don't wait until product or cleaning solution starts to leak.

Air Systems

  • Your maintenance program should cover two types of air systems:

    1. Ambient air is air supplied to the general plant environment, usually through a heating, ventilation and air conditioning (HVAC) system.

    • Identify the components of the HVAC system and include them in the PM program. When components are installed, the installer or manufacturer should tell you which items need servicing and how often they should be serviced.

      - Filters are especially critical. These include high-efficiency particulate air (HEPA) filters, as well as the filters on air intake and exhaust vents into processing rooms.

    2. Product contact air includes air used to move product or air directly incorporated into the product.

    • Identify the components of any compressed air systems in your plant and include them in the PM program . Properly maintaining these components will help to make sure that the product does not become contaminated by dirt, oil and lubricants or their vapours, water or micro-organisms. The tools to do the required maintenance tasks
    • Make sure you have the proper tools readily available to do the work.
    • Some equipment may require specialized tools to access certain parts and/or perform certain maintenance tasks.
A preventive maintenance (PM) schedule
  • Assess each piece of equipment to determine what servicing needs to be done and how often it needs to be done. Base this on:
    • Equipment specifications and manuals - Check the manufacturer's recommendations for servicing and maintenance needs and frequency.
    • Equipment history - All equipment will wear out and break down over time. Knowing the age of the equipment and its repair and service history will help you decide how often to inspect and maintain it.
    • Employee knowledge and experience - Your production operators and maintenance staff can provide valuable insights into the maintenance requirements of particular equipment.
    • Operating requirements - The more frequently a piece of equipment is used and the longer each run lasts, the more frequently the equipment should be serviced.
    • Decide who is responsible for PM on each piece of equipment. For example, is it contracted out to a service company or is it done by plant employees? If it is done by plant employees, which specific employee? For certain equipment, some parts may be serviced by equipment operators while other parts may need to be handled by maintenance staff
  • Develop a PM schedule that keeps track of all equipment, what servicing items need to be done on each one, who is responsible for each item and when that item should be done. You can use simple calendars, card file systems, electronic spreadsheets or commercially available software (for more complicated schedules).

Note: The PM schedule is not a record of what has been done. Instead, it is a record of when tasks should be done.

A method to make sure the scheduled work gets done and documented
  • Along with the PM schedule, create a record system such as a logbook, spreadsheet , card files or work order to track when a particular maintenance item has been completed.
  • This record should include:
    • the name of the equipment (for example, raw milk receiving pump)
    • the date scheduled for maintenance
    • the date the maintenance was actually done
    • a complete list of work done (for example, inspected and replaced rear gasket seal)
    • a list of any parts replaced (for example, rear gasket seal part # xxxxxx)
    • comments (for example, old gasket seal very worn and should be replaced sooner)
    • the name and position of the person who did the work (for example, Joe Smith, maintenance staff)
    • the manager's signature
  • If the work is done by an outside service company, the company should leave a detailed service report that covers this information. A plant representative should review and sign the service report and tell the appropriate plant employees about anything that needs follow-up. Record any follow-up actions.
  • Once the maintenance has been completed, the service person should make sure all tools, parts, etc. are accounted for and removed from the area.
  • When product contact surfaces are affected by maintenance, they should be properly cleaned and sanitized after the repairs are finished and before the equipment is used.

4. Calibration

A calibration program is an essential part of a dairy processor's food safety program. It is important to regularly calibrate any instruments that measure or control parameters (such as temperature, time or pressure) to ensure the equipment meets legal requirements that ensure the product is safe.

Instruments should be calibrated:

  • when a new instrument is acquired
  • after an instrument has been repaired or modified
  • after a period specified by the manufacturer
  • after it has been operated for a number of hours specified by the manufacturer
  • after a shock, vibration or exposure to anything that could put it out of calibration or damage it
  • whenever the readings seem questionable

For example, if a thermometer on a pasteurizer reads higher than the actual temperature, the product will be under-pasteurised. This could mean that pathogens survive and create a potential food safety risk. It could also mean that more spoilage bacteria survive, reducing the quality of the product and shortening its shelf life.

On the other hand, if the thermometer on a pasteurizer reads lower than the actual temperature, the product may get heated to a higher temperature than required for pasteurization. This may give the product a "cooked" flavour. Over-heating may also increase the amount of burnt product deposits on product heating surfaces. Because these deposits are difficult to remove with routine cleaning, they may cause the formation of biofilms that contaminate the product.

Certain instruments must be calibrated according to a schedule. For example, to ensure a pasteurizer meets legal requirements, the following components must be calibrated at a specified frequency :

  • temperature measuring/recording devices
  • temperature control devices
  • timing devices
  • pressure gauges
  • flow meters used to control and monitor the pasteurization process

Other equipment with measurement or recording instruments should also be calibrated regularly. These include:

  • thermometers in freezers, refrigerators, smoke houses, ageing rooms and product storage tanks
  • humidity meters in ageing rooms
  • pH meters
  • laboratory equipment

One person should oversee the calibration program to make sure the schedule is followed to make sure the product is safe and meets legal requirements.

Document your calibration program. This includes:

  • a list of the measuring and controlling instruments that directly affect the safety of the product
  • a list of the calibrations each instrument needs
  • the qualifications and contact information for the employees or the outside service company in charge of doing the calibrations
  • the test procedure used (where applicable)
  • detailed written instructions for calibrating each instrument (for employees)
  • instructions on how to record the results of calibration tests so they are easily understood and meet the format specified by regulatory agencies (if applicable)
  • how often each instrument should be calibrated (most instruments are calibrated when they are installed and then at a specified frequency or whenever a change is made that might affect the parameters being measured)
  • the date of the last calibration and next calibration
  • the maximum error allowed before the instrument must be corrected. For example, a thermometer should be recalibrated when its required accuracy varies by more than plus or minus 0.5°C (±0.5°C)
  • the actual measurements or readings taken during the calibration testing
  • adjustments made to the equipment or instrument if necessary during calibration
  • any corrective action taken if the equipment does not meet your specifications
  • how to identify any product that might have been affected and what to do with it

If an outside service company does the calibration, a plant employee should review the results and approve them.

Instruments should be tagged after calibration. The tag should either list the following information or describe where this information can be found:

  • who did the work
  • the date the work was done
  • the date of the next scheduled calibration

These tags should be made of materials that are water-resistant and oil-resistant.

Note that critical dairy processes should be tested using the Critical Process Test Procedures described in Chapter 18 and Appendix 6 of the Canadian Food Inspection Agency's Dairy Establishment Inspection Manual. Critical processes include:

  • pasteurization (vat, high temperature short time [HTST], higher heat shorter time [HHST])
  • aseptic processing and packaging systems (APPS)
Sealing Calibrated Equipment
  • Instruments that measure and/or control critical processes (such as pasteurization, aseptic processing and packaging, metal detection) must be sealed to prevent unauthorized adjustment to the calibrated settings. This is an important part of a calibration program.
  • The physical seal must be intact on the flow control device (FCD) (such as a positive pump or magnetic flow meter) to make sure that the product is pasteurized for the minimum holding time. Seals are also required on:
    • flow diversion devices (FDDs)
    • safety thermal limit recorders (STLRs)
    • programmable logic controllers (PLCs)
    • resistance temperature detectors (RTDs)
    • pressure differential controllers (PDCs)
  • There must be a program in place to monitor and control the use and replacement of these seals. Keep a record that lists:
    • the seals used
    • a unique identifier for each seal (for example, using a sequential numbering system)
    • where each seal is located
    • when a seal is broken and who was responsible
    • why the seal was broken
    • when the equipment was re-sealed
    • the person responsible for sealing

Training

All employees involved in buying equipment should be trained so that they understand the importance of equipment design in ensuring the production of safe food.

All employees should be trained to:

  • be aware of the normal operating parameters for the equipment they work with
  • know when the equipment may need maintenance or calibration
  • know how this affects the safety of the product

Whether PM is done by employees or an outside service company, the people doing the work must be qualified, either through training or experience. All maintenance employees need to be trained and qualified for the equipment they work on. They should also be trained in the plant's PM and calibration programs.

Monitoring and Follow-up

It is important to periodically (for example, monthly) review your corrective and preventive maintenance records (such as log books and/or work books) to:

  • make sure maintenance tasks are being carried out as scheduled
  • determine if equipment needs replacing
  • determine if servicing needs to be done more often

Plant managers should review all calibration reports to make sure that:

  • all the calibrations were performed as scheduled
  • the calibrations were performed by qualified people using proper calibration tools
  • the correct methods were used
  • the actual readings were recorded (not just "satisfactory" or "non satisfactory")
  • the report was signed and dated
  • any recommended corrective actions have been taken

Resources

  • Dairy Food Safety Advisor, Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA)
  • Canadian Food Inspection Agency's Guidance Documents
  • 3-A Sanitary Standards (hygienic design criteria for dairy equipment and systems)
  • Dairy Food Safety Victoria technical information notes

Templates


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca