With improvements in the handling and transport of hazardous chemicals and with risk being designed out of chemical plants wherever possible, the number of chemical incidents involving the emergency services is decreasing.
Traditionally, chemical protective suits for emergency responders have been manufactured from tough heavy materials that could be used again and again provided the suit could be safely decontaminated each time, but with the reduction in incidents the number of times a suit will be used during its operational life has fallen. At the same time advances in technology for single use suits have seen significant improvements; fabrics are now stronger, lighter and resistant to an extremely broad range of hazardous chemicals.
The net result of these changes is that the economics of ownership for hazmat suits have changed and many fire brigades, along with other emergency responders, are now seriously considering the move to disposable suits. They have realised that with fewer uses over the working life of the suit, it is now often more cost effective for brigades to buy single use suits, replacing them when needed, than to buy a single reusable suit (which is considerably more expensive due to the cost of materials and more complicated methods of construction). For example, for the purchase price of a single Respirex™ GTB suit in a Viton®/Butyl/Viton® material you could buy four Respirex™ Chemprotex™ 400 GTL gas-tight suits – both suits meet the same standards; they are both rated EN 943-2 ET, both offer protection against a broad range of hazardous chemicals, radioactive particulates, infective and chemical warfare agents. It is also worth remembering that on occasion a ‘reusable’ suit may only be able to be used once anyway if the suit cannot be safely decontaminated, which is dependent on the type of chemical/agent with which the suit has been in contact.
Operational Advantages of Disposable Suits
The latest disposable suits are significantly lighter in weight than their reusable counterparts (a GTL is a quarter of the weight of the equivalent reusable GTB), resulting in significantly lower physical stress for the wearer. Recent UK trails have demonstrated reduced levels of heat stress and exhaustion when using modern lighter weight suits. Comfort is also improved as single use fabrics are suppler and less bulky, improving the way the suits fit the wearer and allowing greater freedom of movement, which improves the operational effectiveness of the suit and also aides in donning and doffing. The thinner fabrics also improve sound transmission through the suit, improving communication and situational awareness.
With no re-use of suits, the risks of contact with suits with improper or insufficient decontamination are eliminated and the decontamination process itself is simplified, as the suit only needs to be decontaminated to a point where it can be removed safely from the wearer. There is also no need for hygienic cleaning for single use garments. In industrial applications single use suits also remove the risk of cross contamination. After use modern materials like Chemprotex™ 400 and 300 can be recycled or safely incinerated, simplifying disposal.
With gas-tight suits there is also no need to inspect, repair and re-test disposable suits, which also reduces the cost of ownership. With new suits like the GTL from Respirex able to be stored for seven years (in its sealed bag) without the need for testing, there is a significant saving when compared to traditional ‘rubber’ suits that need to be tested every year.
With space on fire appliances at a premium the smaller pack size and weight is also a distinct advantage of modern single use suits. A single use GTL suit packs into one third of the volume of an equivalent GTB reusable suit.
Advances in Single Use Materials
Modern single use materials, such as the Chemprotex™ range of fabrics from Respirex utilise a laminate constriction method, which assembles multiple different material layers with different physical or chemical properties into one material, giving superior performance to traditional fabrics. With permeation test data available for 120 common chemical hazards Chemprotex fabrics also offer protection against infective agents and over 48 hours hour protection against HD, GB, GD & VX chemical warfare agents (when tested in accordance with Finable 0.7.C).
Chemprotex fabrics are lightweight, and highly flexible with excellent mechanical strength and a soft comfort lining on inside face. They are also engineered to reduce noise (producing a lower ‘rustle’ fabric), which aides comfort and improves communication.
The halogen free material construction allows suits to be incinerated at end of life; alternatively, as the material and the majority of suit components are thermoplastic, suits can be recycled as mixed polyolefin where facilities exist
One key advance in modern materials is the use of toxicity modelling techniques; for example the PermaSURE® app for Chemprotex™ fabrics calculates your safe working time based on the chemical you are working with, the extent of your exposure (e.g what percentage of the wearers body will be in contact with the chemical), the type suit you are using and the actual suit temperature.
Permeation data for chemical protective fabric is an important starting point in the decision process of what suit material to choose for working with a given chemical, and provides an excellent means to compare different fabrics, but permeation data alone does not tell you how long you are safe to work, and if used incorrectly can actually give a false sense of security to chemical workers. There are three reasons why permeation data alone is not enough to make an assessment of safe working time:
- Permeation is measured in a laboratory at 23°C, but in use the temperature of the suit fabric may be much higher or lower. As a rough rule of thumb the rate of a chemical process doubles with every 10°C rise in temperature; PermaSURE® models this accurately. Whether the suit is as warm as the wearer (body temperature is typically 37°C ), or as cold as the surroundings (potentially below 0°C in winter), PermaSURE® gives reliable information about permeation resistance under real operating conditions.
- Breakthrough time, as quoted in permeation tables, measures the time taken to reach an arbitrarily–specified rate of permeation through the suit fabric (typically 1.0µg/cm2/min), but by the time permeation reaches this rate how much chemical has already permeated through to the wearer? PermaSURE® modelling includes the low-level, but potentially-significant permeation, before breakthrough.
- PermaSURE® takes account of the toxicity of the substance your suit is exposed to when calculating a safe working time, thereby discriminating between harmful, toxic and carcinogenic substances, ensuring that the degree of protection matches the potential hazard to the wearer. It also provides clear hazard information.
PermaSURE® also provides useful housekeeping functions like recording of incident numbers on searches and a reporting of the searches carried out by each user or organization, which can provide a valuable post incident audit trail.
Undoubtedly there is still a place for the reusable suit in the hazmat responders’ arsenal as the stronger fabrics provide greater puncture and abrasion protection and if suits are used regularly the economics of decontamination, testing and re-use start to stack in their favour. However, for brigades facing fewer incidents the economics start to look favourable for single use suits, particularly when all of the additional benefits for the wearer and the brigade are considered.
For more information, go to www.respirexinternational.com