Description

Preferred Vacuum Test for Ductwork Cleanliness Inspection

These capsules are pre-weighed and have a unique ID number issued by the independent laboratory. The EVT capsules, previously known as preferred vacuum test capsules, are used to assess ductwork cleanliness in accordance with BS15780 and TR19 guidance. Table 2 of TR19 lays out the acceptable levels of dust accumulation in new ductwork. This method requires on site sample collection and subsequent off site laboratory analysis. It determines the mean deposit weight in grams per m2 and is suitable for circular, flat-oval and rectangular duct types. This method is recommended by BS EN 15780 and applies to three cleanliness quality classes (for ventilation systems).

Carrying out preferred vacuum tests

A capsule is connected to a correctly calibrated vacuum test pump. The sample is collected by vacuuming a 10x10cm area of the ductwork internal surface. The information about each test must be recorded on a test sheet detailing location, ductwork class (low, medium or high) and system type (supply, extract or recirculation). The laboratory weigh the dust deposits within the capsule to determine the overall ductwork cleanliness per m2.