BS EN 148-1:2018 pdf free.Respiratory protective devices -Threads for facepieces Standard thread connection.
BS EN 148-1 The axial dimensions of the male thread connector shall be measured starting from the most protrudingpart of the sealing surface (including raised sealing ring, if present).
The beginning of the thread, up to a maximum of 2 mm of length, is not considered as effective threadand it shall be left to the manufacturer’s design choice.The initiation of the thread shall be smooth.
When the GO gauge is screwed by hand without excessive force onto the male thread connector,at least2 mm of the connector shall extend from the surface of the gauge.
The effective length of thread shall be ≥ 14,5 mm (see Figure 3 and 4).
When gauged with the effective length ring gauge, the distance from the top of the gauge to the top ofthe thread shall be ≥ 8 mm (see Figure 20 and 21).The internal diameter (minimum diameter of the sealing surface area) of the male thread connectorshall be ≤ 33,0 mm (see Figure 2).
lt shall not be possible to fit the NO-GO gauge onto the male thread connector.Without excessive force, the NO-Go gauge shall bind after initial engagement.Testing shall be performed in accordance with 5.1,5.3 and 5.5.
The material used for the female thread connector and its thickness is left to the manufacturer’s choice.
The axial dimensions of the female thread connector shall be measured starting from the sealing surfaceof the sealing element.
The available length of the thread of the female thread connector shall be (13,0±0,5) mm extended tothe edge of the connector (see Figure 5).
When the GO side of the gauge, with ring A in place, is screwed by hand without excessive force into thefemale thread connector (with the sealing element correctly in place), ring A shall block.
When the G0 side of the gauge, with ring B in place, is screwed by hand without excessive force into thefemale thread connector (with the sealing element correctly in place),ring B shall remain loose.
The internal diameter of the female thread connector (minimum diameter of the sealing area) shallbe ≤ 30 mm (see Figure 5).
lt shall not be possible to fit the NO-GO side of the gauge into the female thread connector withoutexcessive force. It shall bind after initial engagement.
lf the central hole of the connector on the respiratory interface has a rim for retention and centring ofthe sealing element, it shall end at least 1 mm below the surface of the sealing element interfacing thefilter.BS EN 148-1 pdf download.