Follow one compressed air line through a seafood processing plant and its risk changes several times. The same supply might operate an enclosed actuator, blow water from processing equipment and reach an outlet beside exposed product. Specifying every outlet to one generic purity class can waste energy in low-risk areas while leaving a critical application under-protected.
Design Air, Atlas Copco Premier Distributor in Scotland, approaches seafood applications from the point of use backwards. The process starts by identifying how air could affect the product, assigning measurable purity requirements and then selecting the compressor, dryer, filtration, pipework and controls needed to achieve them.
For processors in Fife, Tayside and Scotland’s east-coast fishing centres, the calculation must also account for cold pipework, frequent washdown and production schedules that leave little tolerance for interruption.
Map Each Outlet Against Its Contamination Risk
Compressed air purity is an application requirement, not a single compressor-room specification. A useful survey records what each outlet does, where its exhaust goes and whether air can reach food, food-contact surfaces or the inside of packaging.
| Application | Potential contamination route | Specification questions |
|---|---|---|
| Blowing or separating exposed seafood | Air reaches the product directly | Which particle, water and oil limits apply at the outlet? |
| Drying cleaned processing equipment | Residual contamination may reach a food-contact surface | Is the air part of the validated cleaning process? |
| Operating actuators above an open conveyor | Exhaust or leakage may enter the product zone | Where does the actuator vent, and what happens if a seal fails? |
| Pneumatic control inside enclosed equipment | No intended product contact | Could maintenance, pressure loss or component failure create a route to product? |
| Workshop or external utility air | Normally outside the hygiene zone | Is the supply physically separated from higher-purity production outlets? |
This mapping prevents assumptions based solely on distance. An actuator may sit several metres from the product yet exhaust directly over an open line. Another outlet may be physically close but isolated by an enclosure and controlled airflow.
The HACCP team should also distinguish normal operation from credible faults. A damaged hose, failed drain or saturated treatment element may create a contamination route that does not exist when the system is operating correctly.
Turn the HACCP Assessment Into an Air Specification
Regulation (EC) No 852/2004, now assimilated law in Great Britain, requires permanent procedures based on Hazard Analysis and Critical Control Point principles. These cover hazard identification, critical control points, critical limits, monitoring, corrective action, verification and proportionate records.
Compressed air therefore needs to sit within the plant’s wider contamination-control system. That does not mean declaring every outlet a critical control point. It means documenting the air-related hazard and deciding how it will be controlled.
A practical assessment proceeds in this order:
- Record every outlet, its function, flow, pressure and operating pattern.
- Identify credible particle, water, oil and microbiological hazards.
- Decide whether air has direct contact, indirect contact or no plausible contact with product.
- Document the control approach for each relevant contaminant.
- Define monitoring, corrective action and verification responsibilities.
- Review the assessment when products, equipment or processes change.
A new packing machine, altered shift pattern or relocated air drop can invalidate an earlier assessment. The legislation specifically requires HACCP procedures to be reviewed when a product or process changes.
Select ISO 8573-1 Classes by Application
ISO 8573-1:2010 (iso.org) provides separate compressed air purity classes for particles, water and oil. It also identifies gaseous and microbiological contaminants. The three categories should be considered independently because a system that controls oil effectively may still deliver unsuitable moisture or particle performance.
An ISO 8573-1 class is an acceptance criterion for air at a stated location, not a description of the compressor alone.
The specification should therefore identify:
- the outlet or group of outlets covered
- the required particle, water and oil classes
- the operating pressure and flow range
- the test location and applicable test method
- whether microbiological assessment is required by the HACCP study
- the action to take after an out-of-limit result
Avoid copying a class from another factory without comparing the processes. Air used inside a sealed pneumatic circuit presents a different hazard from air blown onto an exposed fillet. The tighter class may be justified for both in a particular plant, but that decision must come from the documented risk rather than a generic food-industry label.
Match the Dryer to the Coldest Part of the System
Pressure dew point is the temperature at which water vapour begins to condense at the operating pressure. If compressed air or downstream pipework becomes colder than its pressure dew point, liquid water can form even though the air appeared dry when it left the compressor room.
This matters in seafood plants where lines pass through chilled production rooms, unheated loading areas or external sections. Our guide to compressed air moisture issues explains the wider causes and effects. For system selection, the important figure is the lowest temperature the treated air will encounter under actual production and shutdown conditions.
Refrigerated Drying
A refrigerated dryer cools compressed air so moisture condenses and can be removed. It can be an efficient choice where the required pressure dew point remains safely below the lowest downstream temperature.
The UK Energy Technology List reports that a refrigerated dryer typically adds 2% to 5% to compressed air system energy use (etl.energysecurity.gov.uk). Demand-responsive models typically use 30% less energy than non-modulating units. Dryer controls therefore matter when seafood production varies between landing schedules, shifts or seasonal throughput.
Desiccant Drying
A desiccant dryer removes water vapour by adsorption rather than relying on cooling alone. Atlas Copco’s dryer-selection guidance (atlascopco.com) states that desiccant drying commonly delivers a −40°C pressure dew point, with −70°C options for more demanding duties.
That does not make desiccant drying the automatic answer for every outlet. Regeneration consumes energy, and conventional heatless designs can use a material proportion of rated airflow for purge. A warm, enclosed utility circuit may not need the same treatment as a line passing through a Fraserburgh dispatch area in winter. Site measurements and equipment correction factors remain necessary before the recommendation is settled.
Design the Treatment System From the Outlet Backwards
The compressor is only one part of the purity system. Compressor type, contaminant separation, filtration, drying, distribution materials and operating controls all affect the result.
The design review should establish which functions are required:
- treatment for liquid water where identified as a hazard
- removal of oil and water aerosols where identified as hazards
- removal of solid particles to the specified class
- water-vapour reduction to the required pressure dew point
- control of oil vapour where the HACCP assessment requires it
- corrosion-resistant distribution through wet or saline areas
- accessible locations for representative sampling
Component order, filtration grade and capacity depend on the selected equipment and its inlet limits. A filter that receives more liquid than it was designed to handle may not deliver its rated downstream performance. A dryer sized only for average flow may also be overloaded during cleaning or peak processing periods.
Pipework deserves the same attention. Internal corrosion, retained condensate and poorly controlled extensions can change air quality after the treatment equipment. An ultrasonic leak detection survey can quantify losses and distinguish avoidable demand from genuine process growth. The air class should be specified at the location relevant to the process, with the sampling plan designed around that location.
Protect Production While Maintaining Purity
Seafood plants rarely have the option of stopping every pneumatic process while one compressor or dryer is serviced. Resilience may require shared compressor capacity, duty and standby treatment equipment, isolated production zones or planned storage. The correct arrangement depends on which loads must continue and for how long.
Condition monitoring can track pressure, running hours, temperature, dryer performance and filter differential pressure. Used properly, it can identify deteriorating performance before it becomes a production interruption – see our guide to reduce costs and downtime the role of ai in air compressor monitoring.
System demand also affects resilience. Unrepaired leaks consume capacity that should be available for peak production or standby cover.
When a fault does stop production, the purity controls still apply during recovery. Temporary equipment and replacement components need to match the relevant outlet specification. Design Air’s compressor repair service supports fault diagnosis and restoration without treating air quality as separate from the repair.
Verify Performance Under Operating Conditions
Commissioning demonstrates initial performance.
The verification plan may combine:
- pressure dew point trending
- filter differential-pressure checks
- drain inspection and alarm testing
- particle, oil and water measurements using relevant ISO 8573 methods
- representative outlet sampling
- maintenance and calibration records
- documented investigation of adverse trends or failed results
ISO 8573 includes different test methods for different contaminants. For example, ISO 8573-9:2004 (iso.org) covers measurement of liquid water content. The method selected must match the contaminant and acceptance limit being assessed.
A single compressor-room sample cannot answer every process question. Verification locations should reflect the written specification, particularly where long pipe runs, cold rooms or different treatment branches separate the source from the application.
Prepare the Information Needed for a System Assessment
Generic purity tables cannot resolve the coldest pipe temperature, peak flow, contact route or acceptable interruption time for a particular factory. Those details determine both compliance and operating cost.
For a useful assessment, provide:
- an outlet schedule with contact categories
- required flow, pressure and duty cycle
- existing compressor and treatment details
- production-room and external temperature ranges
- washdown conditions and hygiene zoning
- current monitoring or air-quality test results
- planned equipment or capacity changes
- the production loads that require standby cover
Our factory-trained engineering team can use this information to develop an outlet-specific purity schedule, dryer and filtration specification, pipework plan, monitoring approach and capacity assessment. Where energy use is material, the review can also include dryer controls, system pressure and avoidable demand.
To arrange a compressed air system assessment for a seafood processing plant in Scotland, contact Design Air with your current outlet schedule, production profile and air-quality requirements.