Source ext­rac­tion

Source ext­rac­tion, also cal­led local exhaust ven­ti­la­tion, is the reco­ve­ry of mor­tar dust, cut­ting dust, abra­si­ve dust or other impu­ri­ties in the con­struc­tion that occurs near (less than 50 cm) its source of birth. Source ext­rac­tion devices are cost effec­ti­ve due to the small dis­tance, because the requi­red suc­tion power is small and the­re­fo­re advan­ta­geous to imple­ment. In addi­tion, it is fas­ter and more efficient to col­lect dust whe­re it is gene­ra­ted befo­re it is relea­sed into the envi­ron­ment. Cer­tain faci­li­ties and con­di­tions may requi­re the use of source ext­rac­tion devices, which may be sta­ted by the con­struc­tion subsc­ri­ber in the cont­ract.

When using source ext­rac­tion devices, con­struc­tion work can pre­vent the sprea­ding of dust, which is hazar­dous to health, such as quartz con­tai­ning dust and other con­ta­mi­nants on the site, and get­ting into the wor­ker’s breat­hing zone and the lungs.

Source ext­rac­tion met­hods are divi­ded into high and low pres­su­re devices based on the mag­ni­tu­de of their nega­ti­ve pres­su­re.

High pres­su­re source ext­rac­tion

An effec­ti­ve met­hod for remo­ving dust from, for example, dus­ting, sawing and grin­ding work is to use high-pres­su­re, mic­ro­fibre and HEPA fil­te­ring units. The­se inclu­de buil­ding vacuum clea­ners and cent­ral vacuum clea­ners. In the­se devices, the suc­tion line is con­nec­ted direct­ly to the device. The rule of thumb is that a high-pres­su­re device has a very small suc­tion area and suc­tion is clo­se to the source of dust. In this case, a rapid airflow is crea­ted near the proces­sing point, which cap­tu­res the impu­ri­ty at its for­ma­tion. The speed of the airflow is very high in order to reco­ver coar­se impu­ri­ties such as sand and chips. Sur­veys show that high-pres­su­re source ext­rac­tion gives about 80–90 % dust reco­ve­ry.

Low pres­su­re source ext­rac­tion

At low-pres­su­re source ext­rac­tion, the air volu­me is high com­pa­red to the high-pres­su­re devices, but the airflow rate is qui­te low. The equip­ment’s cap­tu­re dis­tance is also grea­ter than in high-pres­su­re source ext­rac­tion. The­re­fo­re light air­bor­ne par­ticles are reco­ve­red from a wide ran­ge. The remo­vable source ext­rac­tion device is placed in the imme­dia­te vici­ni­ty of a dus­ty job such as mor­tar mixing or demo­li­tion work.

The Con­sair CAMU is an example of a source ext­rac­tion device, i.e. a dust cont­rol works­ta­tion. Other low-pres­su­re source ext­rac­tion devices inclu­de air puri­fiers and nega­ti­ve pres­su­re units.

Read more about mixing tents and source ext­rac­tion devices in dust cont­rol.