BS EN 893 pdf free download

BS EN 893-2019 pdf free download.Measurement of the concentration of particulate material in ducts carrying gases.
4.2 General requirements concerning equipment. Unless specifically agreed otherwise between the interested parties, all apparatus to be inserted into the duct shall be suitable for insertion through a hole of 109.8 mm diameter, even with thick-walled ducts. This corresponds to the bore of a socket which will accept a pipe threaded externally to series R4 of BS 21. The apparatus required for measuring the chemical composition of the gases is not dealt with in this British Standard (see BS 1756). Equipment shall be provided and measures shall be taken to ensure the safety of personnel, including the following:
a) an adequate and safe working platform at each sampling position, with safe means of access to it;
b) protection for the personnel taking the measurements, including protection from the gases in the flue, as necessary;
c) safe means of handling the equipment in use;
d) the safety of those below the sampling position.
4.3 Entry nozzle (see Figure 2). The entry nozzle is that part of the equipment which first admits a sample of the gas stream to be measured. The nozzle should be of a simple design, as shown in Figure 2, and should not include any encumbrances that might affect the performance of the equipment. Other designs of nozzle may be used provided that they comply with the accuracy requirements of this standard. It is usual for a range of different internal diameter nozzles to be supplied with the equipment so that samples can be withdrawn from gas streams flowing at a wide range of velocities. The external profile of the entry nozzle should be similar to that shown in Figure 3 or Figure 4. No reduction should be made in the internal diameter over a distance equal to three times the diameter of the entry section. Any subsequent changes in bore diameter shall be tapered rather than stepped. Any bends in this section shall have a minimum radius of 1.5 times the nozzle bore diameter. In order to obtain a sharp-edged entry section, the width of the annular face of the tip of the nozzle should be not greater than the dimensions shown in Figure 3 and Figure 4. The diameter of the entry nozzle shall be not less than 10 mm.
4.4 Probe tube. The probe tube is that part of the equipment which enables the entry nozzle to be placed within the duct or chimney in order that a sample of gas may be taken. The probe tube usually connects together the different items of equipment, namely the entry nozzle, particle collector(s) and separator(s), and also the sample flow rate measuring device where this is in the duct. Any part of the probe tube that is within the duct shall be rigid.
The probe tube shall be fitted with a pointer or other device to indicate the direction in which the entry nozzle is pointing. All internal parts of the probe tube shall be smooth and well polished, where necessary, and the number of joints should be kept to a minimum. Where necessary, provision shall be made for recovering any solids deposited in the probe tube. Provision shall be made, if necessary, for the heating or the cooling of the probe tube (see 6.8 and 6.9) without impeding its handling capabilities.BS EN 893 pdf download.