Nega­ti­ve pres­su­re unit for dust control

A popu­lar way to per­form pas­si­ve dust cont­rol is using a nega­ti­ve pres­su­re unit. In prac­tice, this is done by com­part­men­ta­lizing the area whe­re the dust is gene­ra­ted. Par­ti­tio­ning is usual­ly ina­dequa­te for dust pre­ven­tion. The­re­fo­re, a requi­red num­ber of nega­ti­ve pres­su­re units are placed in the com­part­men­ting space to make the repair area under-pres­su­rized rela­ti­ve to the sur­roun­ding spaces.

From the com­part­men­ted and pres­su­rized space, air is remo­ved so that the replace­ment air flows from the clean space to the dir­ty space. The con­ta­mi­na­ted exhaust air is gene­ral­ly direc­ted to the open air through a plas­tic tube.

The nega­ti­ve pres­su­re devices should be posi­tio­ned on the dif­fe­rent sides of the space to be repai­red, so that the lar­gest pos­sible area is wit­hin the ven­ti­la­tion area. The nega­ti­ve pres­su­re must be main­tai­ned con­ti­nuo­us­ly and under all circums­tances and moni­to­red by means of gau­ges. The nega­ti­ve pres­su­re is main­tai­ned until the final clea­ning to make sure the desi­red level of puri­ty is achieved.

Dimen­sio­ning the nega­ti­ve pres­su­re units or air purifiers

The design of the nega­ti­ve pres­su­re units must take into account the reduc­tion in power when the fil­ter is loa­ded. Device speci­fic pres­su­re gene­ra­tion and air volu­me data are used to select the right num­ber of devices and their types.

Visual­ly, nega­ti­ve pres­su­re can be seen from the plas­tic walls used in the com­part­ment, which are pres­sed toward the nega­ti­ve pres­su­red space by the airflow. The vacuum should be 5–15 Pa and the air should chan­ge 6–10 times per hour. Replace­ment air is set to be about 20% less than the air remo­ved. Pre­fe­rably, the replace­ment air is con­veyed out­si­de the buil­ding. Howe­ver, the appropria­te tem­pe­ra­tu­re of the replace­ment air must be taken care of.

Too high a nega­ti­ve pres­su­re is harm­ful. It can break the seals of the com­part­ment walls, the doors do not open and the ope­ra­tion of the ven­ti­la­tion sys­tem can be dis­tur­bed. Replace­ment air may enter the wor­king space through, for example, mois­tu­re-dama­ged struc­tu­res con­tai­ning microbes.

Nega­ti­ve pres­su­re in dry-mixing

A lot of dan­ge­rous buil­ding dust is for­med in the mixing of the dry mat­ter, and a nega­ti­ve pres­su­re mixing tent is a gene­ral way of cont­rol­ling dust.

The mixing tent works well in pas­si­ve dust cont­rol, as long as the mixing tent is hand­led care­ful­ly, the fil­ters are ser­viced dai­ly and the nega­ti­ve pres­su­re unit is lar­ge enough – in addi­tion, the worker’s must remem­ber to use a res­pi­ra­tor, as the tent does not pro­tect them, only the surroundings.

Source ext­rac­tion is acti­ve dust cont­rol. It is pre­ven­ting the spread of dust at the time it is crea­ted. Source ext­rac­tion devices such as CAMU will save your steps as it moves whe­re you work.

Learn more about how to use a mixing tent and a source ext­rac­tion devices for dust cont­rol at a con­struc­tion site.