7.(a) Sketch a Chemical Filter tower supplying air suitable for breathing and diving, labelling ALL elements.(4)
(b) Explain the purpose of TWO of the filter elements sketched in part(a).
Chemical Filter tower supplying air suitable for breathing and diving
A chemical filter tower used for supplying air suitable for breathing and diving is a critical component in a compressed air system, responsible for removing harmful contaminants and ensuring the air meets stringent purity standards.
Construction and Design:
- Pressure Vessel: The tower is typically a robust, high-pressure vessel made of steel or aluminum, designed to withstand the high pressures of compressed air.
- Filter Cartridges: Inside the tower, multiple filter cartridges are arranged in series. Each cartridge contains specific filter media designed to target different contaminants.
- Inlet and Outlet Connections: The tower has inlet and outlet connections for the compressed air to flow through.
- Drain Valve: A drain valve at the bottom allows for periodic removal of accumulated moisture and contaminants.
- Pressure Gauge: A pressure gauge may be installed to monitor the pressure drop across the filter tower, indicating when the cartridges need replacement.
Filter Media and Contaminant Removal:
The filter cartridges within the tower contain various types of filter media to remove specific contaminants from the compressed air:
- Moisture Removal:
- Desiccant Material: Absorbs moisture from the air, preventing condensation and potential regulator freeze-up in diving applications.
- Molecular Sieve: Another type of desiccant material that selectively adsorbs water molecules.
- Oil and Hydrocarbon Removal:
- Activated Carbon: Adsorbs oil vapor and hydrocarbon contaminants from the air, ensuring clean and safe breathing air.
- Coalescing Filters: Combine small oil droplets into larger ones, which can then be easily separated and removed.
- Carbon Monoxide (CO) Removal:
- Hopcalite Catalyst: A catalyst that converts toxic carbon monoxide into harmless carbon dioxide.
- Particulate Removal:
- Particulate Filters: Trap dust, dirt, and other solid particles, preventing them from entering the breathing air and causing respiratory irritation or equipment damage.
Operational Considerations:
- Flow Rate and Capacity: The filter tower’s size and capacity should be selected based on the compressor’s flow rate and the desired air purity level.
- Cartridge Replacement: The filter cartridges have a finite lifespan and need to be replaced periodically based on usage and the manufacturer’s recommendations.
- Pressure Drop: The pressure drop across the filter tower should be monitored regularly. A high pressure drop indicates clogged filters that need replacement.
- Air Quality Testing: Regular air quality testing is essential to verify the effectiveness of the filter tower and ensure the air meets breathing air standards.
Importance in Diving:
- Breathing Safety: In diving, where breathing air is supplied at high pressures and depths, the quality of the air is critical for the diver’s safety. The filter tower removes contaminants that could cause respiratory problems, equipment malfunctions, or even life-threatening situations.
- Regulator Protection: Oil and moisture can damage sensitive components within the diving regulator, potentially leading to malfunctions or free flows. The filter tower helps protect the regulator and ensure its reliable operation.
In summary, a chemical filter tower is a vital component in compressed air systems used for breathing and diving. It removes various contaminants, ensuring the air is clean, dry, and safe for human respiration, even under the demanding conditions of underwater environments.