Glossary

Activated Carbon Filters
Also known as: Gas filter,chemical layer
Purex filters incorporate a layer of high efficiency chemical adsorbent to capture and lock in hazardous gas from the contaminated process before clean filtered air is returned to the workplace.

Bulgin
A kind of connector

Filter Indicator
If a filter is nearly blocked or if the gas or particle alarms are triggered, this icon will show which filters may need attention.

Filter Saturated
Constantly monitors the carbon filters to warn the user when they are nearly saturated. This helps reduce downtime by allowing the user time to make replacement filters ready.

Filter Status
Constantly monitors the particle filters to warn the user when they are nearly full. This helps reduce downtime by allowing the user time to make replacement filters ready.

Flow Control
As a filter becomes full, the resistance to airflow increases. This causes the extraction rate to fall, potentially allowing hazardous fumes to enter the workplace. To prevent this happening Purex systems use "Flow Control" to automatically increase the speed of the motor to keep the extraction rate constant.

Gas Sensor
Constantly monitors the chemical filters to warn the user when they are nearly saturated. This helps reduce downtime by allowing the user time to make replacement filters ready. Gas sensors also warn the user if hazardous gas is passing through the system, e.g. due to a missing, damaged or incorrectly fitted filter.

Graphic Display
The 'live' status of the machine is shown on a clear, easy to read graphic display.

HEPA Filter
Also known as: HEPA,High Efficiency Particle Air Filter
In independent tests, Purex HEPA filters removed 99.997% of all particles above 0.3 microns and 95% down to 0.01 micron.

Interfacing
Allows the Purex unit to communicate with associated equipment, options include:

  • Synchronised STOP/START
  • Automatic run on
  • Filter Alarm Signals

Labyrinth Pre-filter
The Labyrinth™ pre-filter is unique to Purex. It's patented design presents more filter fibre surface area to the airflow than other filters on the market, allowing the filter to capture more particles before it becomes blocked. The special material used has a graduated fibre density i.e. there are fewer fibres per unit area at the air entry to the fabric but the density increases towards the air exit layer. This allows the fibres to collect more dust before the filter becomes blocked. This means the filter lasts longer and is therefore more cost effective.

LEV
Also known as: L.E.V,local exhaust ventillation
Local Exhaust Ventilation System - In our opinion the best system to use is an LEV system such as a Purex. These capture fumes at the source thereby preventing fumes escaping into the workplace. They also filter hazardous particles and gasses which would otherwise be pumped into the outside environment causing pollution. Using an internal filter system also avoids issues with environmental regulations and potential complaints from neighbouring businesses about fumes and odours. Purex LEV systems sit next to the process and the extraction rate can be altered precisely to suit the application. Purex machines are also easy to move if the process moves.

Particle Sensor
Constantly monitors the particle filters to warn the user if hazardous particles are passing through the system, e.g. due to a missing, damaged or incorrectly fitted filter.

Safety Sensors
Hazardous gas or particles can pass through a filter system if the filter is damaged, not fitted correctly or is missing. Purex systems incorporate gas and particle sensors as standard to warn the operator if hazardous fumes bypass the filter, this further protects people in the workplace. The sensors also alerts the operator when the chemical filter is saturated or the particle filters are blocked.

Speed Control
The user can set the required airflow for the process. The motor will automatically speed up or slow down until the "actual" airflow equals the "required" airflow. This system is more efficient as the motor does not have to constantly run at 100%. It also means the machine is quieter, uses less energy and the filters last longer.

Temperature Sensor
An adjustable safety alarm to warn if the internal temperature of the machine goes above a certain level.

Vacuum Control
Control of flow by vacuum measurement at the inlet to unit. The negative static pressure (vacuum) is measured via a sense pipe at the inlet to the unit, connected to a single port transducer on the Control Board. The software compares this value with a target value (set wg) set by the operator and causes the blower to speed up until the two values are equal i.e. the flow is maintained at a constant level. Benefit: Slows the blower as tips or arms are closed on the system so maintaining constant extraction at each work station. Also saves energy, particularly on larger machines.

VariColour
A Visual and Audible Filter Blocked Warning. Alerts the operator when a filter starts to block so that a replacement filter can be acquired and downtime can be avoided. LED Filter Status: Green = Filter OK Yellow = Filter nearly full Red = Filter full, replacement required

Volume Control

The air speed in the final discharge duct from the blower(s) is determined using the Pitot principle. This involves measurement of total pressure (static pressure and velocity pressure), in the pipe together with the static pressure alone.

The sense ports are connected by short tubes to a twin port transducer on the new Digital Control board.  The software subtracts the static pressure from the total and derives the air speed from the velocity pressure value.

Benefits:

  • Any obstruction which causes the airflow through the system to fall (E.g. a label from a packaging line entering the pipe work. ) will result in the blower increasing speed to bring the flow back to the selected value or trigger the alarm. All sensing is carried out on the clean side of the filters, i.e. less chance of sense pipe blockage.
  • Continuous visual confirmation that the system is achieving the control parameter required under the COSHH regulations or equivalent.
  • Where multiple systems are being installed on similar processes, the operating parameters can be set on the first extractor and then simply replicated onto the remaining systems regardless of the hose configuration.