The importance of periodic ventilation and air quality measurements

In confined spaces, air quality control is essential. This is possible through knowledge of pollutant emissions, measurements of the concentration of harmful gases in the air and the proper functioning of the ventilation system.

Knowledge of pollutant emissions

The possible pollutants present in the confined environment are identified beforehand in the ventilation study. The most common ones are :

Gases concerned by the VLEP
Dust
VOCs
Asbestos

To evaluate the emissions of polluting gases from diesel-powered machines, it is recommended that measurements of exhaust gas content be taken every 500 working hours (RGIE).

Measurements of dust levels in the air

Inhalable and respirable dusts are among the specific pollutions.

Monitoring the presence of dust allows the protection of workers in the short and long term. Their exposure to dust can be measured by a CIP10 individual dust sampler.

Inhalable and respirable dusts are among the specific pollutions.

Monitoring the presence of dust allows the protection of workers in the short and long term. Their exposure to dust can be measured by a CIP10 individual dust sampler.

Concentration measurements of harmful gases in the air

These pollutants are measured or analyzed following individual or ambient sampling at various points and in particular in the work areas and workstations. The main measuring device to evaluate the air quality is the multi-gas analyzer.

Depending on the problematic of the building site, SUB’ROCA can recommend the installation of the SENSOR’BOX, a fixed multi-gas beacon which controls the air quality, signals alerts of exceedance and allows to export the measured values for fine analysis.

Checking the operation of the ventilation system

The correct operation of the ventilation system can be checked on different points:

Control of the good condition of the ventilation system
- Measurement of the power consumption
- Presence of vibration
Measurement of the air speed in the gallery and calculation of the air flow
Measurement of the air velocities in the duct and calculation of the air flow rate
Performance of a dust collector in its capacity to filter dust
Continuous measurements by measuring devices installed on the ventilation equipment

The correct operation of the ventilation system can be checked on different points:

Control of the good condition of the ventilation system
- Measurement of the power consumption
- Presence of vibration
Measurement of the air speed in the gallery and calculation of the air flow
Measurement of the air velocities in the duct and calculation of the air flow rate
Performance of a dust collector in its capacity to filter dust
Continuous measurements by measuring devices installed on the ventilation equipment

The main measuring devices for checking the ventilation system are the propeller/hot-wire anemometer and the liquid or electronic pressure gauge. Smoke tests should be carried out, if necessary, in order to identify and correct any « dead » zones and to analyze the air flows.

Planning of periodic inspections

Controls at the operator’s expense

The periodic measurements are carried out at the expense of the operator who appoints an internal person in charge of the subject of the ventilation.

SUB’ ROCA proposes trainings of the personnel to help the operator in this mission.

These periodic measurements are to be carried out at least at the beginning of the building site and each time there is a change of nature of ground, of section, of process of digging, according to the following periodicity (to be adapted to the case by case):

– Gas: daily and instantaneous,

– Dust/fibers: monthly at least (including % free silica),

– Asbestos: weekly at least in potentially asbestos-rich soils or after proven identification.

The supply and exhaust air flows, air velocities and duct pressures shall be measured regularly. These measurements should be carried out in particular when there are doubts about the performance of the ventilation, when the installations have been modified or significantly extended. For this purpose, it is recommended to install anemometers, flow meters, manometers on the ventilation network with direct reading.

Controls carried out by an external consulting firm

In assistance to the realization of periodic controls of ventilation and air quality SUB’ROCA will establish :

- The strategy of samplings,
- The realization of the samplings,
- The analysis of the samples with respect to the limit values of professional exposure,
- The necessary preventive measures.

SUB’ROCA recommends to its customers the following periodic controls:

- Measurements of exhaust gas content of combustion engine machines every quarter or every 500 working hours of the machine
- Annual updtae of of the ventilation network
  - Control of the ventilation equipment
  - Taking into account the geometrical modifications of the structure (dimensions, modified air passages, …)
  - Measurement of the main and secondary air flows
  - Control of the tightness of the dams, SAS, doors

- Annual measurements of dust exposure on operators
  - Measurement campaign with CIP10 dust samplers
  - Analysis of samples in laboratory

Controls carried out by an external engineering office

In assistance to the realization of periodic controls of the ventilation and the quality of the air SUB’ ROCA will establish:

- The strategy of samplings,
- The realization of the samples,
- The analysis of the samples with respect to the limit values of professional exposure,
- The necessary preventive measures.

SUB’ROCA recommends to its customers the following periodic controls:

- Measurements of exhaust gas content of combustion engine machines every quarter or every 500 working hours of the machine
- Annual updtae of of the ventilation network
  - - Control of the ventilation equipment
    - Taking into account the geometrical modifications of the structure (dimensions, modified air passages, …)
    - Measurement of the main and secondary air flows
    - Control of the tightness of the dams, SAS, doors

- Annual measurements of dust exposure on operators
  - Measurement campaign with CIP10 dust samplers
  - Analysis of samples in laboratory

The SUB’ROCA engineers are at your disposal to assist and advise you in the dimensioning of your ventilation installations. Whether your project concerns a meshed network in an underground mine or a complex digging project in another environment, our teams have the technology to calculate the air requirements and performance necessary to ensure ventilation that complies with the health and safety of personnel.

Contact our engineering office