What is Evidence Drying?
Forensic evidence drying requires constant controlled low humidity conditions for evidence while containing any air-borne pathogens, particulates, fumes, and odours to protect the personnel and the evidence.
Automatic drying cabinets can be used in forensic evidence drying to protect your staff and preserve the chain of evidence custody providing a clean, secure environment for storing and drying a wide range of forensic evidence recovered from a crime scene.
Cabinet "air dries" wet or damp items of evidence containing biological fluids (blood, sperm, body fluids, etc.) and/or trace evidence in a constant drying medium while protecting laboratory personnel from odors, gases and particulates. The personnel is also protected from infectious pathogens from escaping into the surrounding air while reducing possible cross-contamination of evidence ensuring a safe working environment with filtration.
How Should Evidence Drying Be Made?
There are two main considerations in evidence drying applications: Drying and Filtration. The first function ensures protection against corrosion, growth of bacteria and mould, while the second one reduces the risk of cross contamination between the evidences and the outer ambient.
The drying function is explained in detail at the other pages of this web site. Here a brief information is given about the filtration.
The filtration used in evidence drying has two parts as pre-filtering and exit filtering.
Pre-filtering means the filtering of the air intake to the cabinet to ensure it is clean. This is usually done with HEPA (High Efficiency Particulate Arresting) filters of trapping particles at different size down to a few microns. HEPA-filtered environment ensures integrity of forensic evidence. It is better to locate the air intake pre-filter on the front top of the cabinet to let the air to be drawn down from the top front of the cabinet and exhausted through the bottom. Since room air is usually cleaner near the ceiling, this unique approach prolongs the working life of the air intake pre-filter.
Pre-filters of the cabinet should be inspected and replaced every 3 to 6 months under normal use or when it becomes discolored. They should be changed easily and no special tools should be required to change pre-filters.
Exit filtering captures vapours, odours and particulates given off while drying by both special carbon and HEPA filters. HEPA Filters at exit filtering provides high protection of personnel from particulates, airborne hazards, submicron contaminants including viral and bacterial pathogens to 99.997% at 0.3 microns. Special carbon (activated charcoal) filters eliminate chemical vapours, odours and other gases appeared during the storage and drying of the evidence. HEPA and carbon filters are bonded together in most of the systems.
Exit filtering is usually located in the bottom of the cabinet and have a working life from 24 to 36 months under normal use. This filters should be easily changeable by operator as pre-filters.
Drying cabinets may be supplied with a complete set of filters to be ready to change when necessary.
Constant airflow through the filters should be supplied by high quality fans. A low airflow alarm may be activated if the air velocity reduces when the filters are partly blocked.
Adequate storage space with versatile storage compartments and construction quality are important factors which prevent cross contamination of evidence. Corrosion free stainless steel or white polypropylene interiors should easily drain to reservoir for easy cleaning/disinfection. In addition to this, a drainage solution should be supplied. It may be a gravity drain located well above the floor for proper drainage into a floor drain via a drainage hose or a waste pump for when drainage is difficult due to location.
Doors should be made with transparent vision panels and have locks preventing unauthorized access to insure evidence security.
Fluorescent light inside of cabinet and timing of evidence drying cycle are practical features for the operator’s comfort.
Lockable rubber casters are usable to move easily from one location to another in your laboratory.
An appropriate drying cabinet should be choosen by evaluating the information above.
