Gravimetric analysis samples require filters to be weighed both before and after sampling to determine the amount of contaminants collected. Zefon pre-weighed cassettes eliminate the inconvenience of pre-weighing the filters by providing cassettes preloaded with a PVC filter weighed to within 0.00001g (10µg). The weight and serial number is then printed on the cassette label.
Zefon begins the process of manufacturing pre-weighed cassettes by letting each filter equilibrate to the environmental conditions of 68° F and 50% relative humidity. Filters are then weighed using advanced microbalance equipment which records the weight. After reading the weight, filters are removed, placed into cassettes and sealed with a label bearing the weight and a unique serial number.
Environmental conditions can have a significant effect on filter weight readings. When using Zefon pre-weighed cassettes, it is important that the post sample weighing is performed under the same environmental conditions used at the Zefon factory. Those conditions are set at a temperature of 68° F (± 1.0°F) and a relative humidity of 50% (± 1%).
Using Zefon pre-weighed cassettes does not comply with OSHA directives which require both the "tare weight” and"secondary weight” to be performed on the same microbalance and environmental conditions. If complying with this directive is a concern, match-weighed cassettes are a good alternative way to save time and still comply with the directive.
- 2 or 3 piece housing
- Preloaded, ready to use
- Each cassette labeled with serial number
- Red-colored label bands indicate a 5 micron PVC filter type for ease of identification.
- 5 Decimal weight accuracy (.00001g)
- Use of Pure Homopolyer PVC filters provide excellent weight stability
- PVC filters specially designed with no silica and low ash properties