Ventilation Monitoring

Despite the relaxation of restrictions, Covid-19 remains a very real threat.

As the main danger is via exhaled droplets and aerosols, good ventilation is essential to reduce the chance of transmission. Ensuring that ringing rooms are adequately ventilated will be essential to the continuation of ringing over the coming months, and will also help to build confidence among ringers and the church.

Having accurate information about individual ringing rooms can help to answer questions such as:

Is the current ventilation is adequate or does it need improvement?
Is it safe to reduce the amount of ventilation in colder weather?
Is the ventilation sufficient to allow longer periods of ringing or larger numbers of ringers?

The CCCBR have published a paper by Dr David Pouncey suggesting that measuring changes in the level of carbon dioxide present provides an effective way of measuring this.

The Derby City Centre Ringers have invested in one of the suggested monitoring devices, a Dracal PicoCO2 USB-DXC100, allowing us to carry out measurements at St Peter's. It is also available for use at other towers. If the results are shared then it will also benefit the wider ringing community by contributing to further research. This data will help develop strategies to allow ringing to continue in the face of a resurgence of the virus, particularly

Measuring Air Changes per Hour

Results

About the sensor

The sensor measures these values:

CO2 concentration
Temperature
Relative humidity

The sensor needs to be connected to a PC USB socket - preferably a laptop to make it easier to use in the tower.

The PC needs to have the free Qtenki software installed. This can simultaneously record or display the values being measured in the following ways:

Current value
Minimum/Maximum value
Real time graph
Log file

Additional calculated values can also be recorded or displayed.

Example Results

Results at St Peter's showed that the ventilation in the tower is sufficient with six ringers (the maximum currently allowed). The results can be downloaded here.

Results at St Giles', Sandiacre, showed that additional work was required in order to provide adequate ventilation. Once this was carried out, a second set of results showed that the ventilation was at an adequate level. The results can be downloaded here.

Borrowing the sensor

The sensor will be loaned under the following conditions:

There will be a charge of £10 to help defray the cost of the equipment, payable in advance. Subsequent loans for use at the same tower (e.g. to check the results of changes to the ventilation arrangements) will be charged at £5.
The results of any monitoring will be shared with the CCCBR.
Only the Dracal PicoCO2 and a USB extension cable will be supplied. The person borrowing it will be responsible for providing a suitable PC and for downloading/installing the free QTenki data logging software.
Loans will be for a period of up to 8 days, including time taken to collect/return the equipment (longer periods subject to agreement).
The person borrowing the equipment will arrange collection and return from Derby (or another agreed location), or will pay for delivery by a tracked courier. This will not cost much - it will easily fit in an A4 padded envelope.
If the equipment is not returned, or is returned in damaged condition, then the Derby City Centre Ringers will be compensated with the full cost of replacing the equipment, including delivery costs (less the loan fee).

If you are interested in using this equipment to check the ventilation in your tower, then please contact us.

Instructions

The PicoCO2 sensor is easy to set up and use. With advance preparation it should be possible to carry out the necessary measurements within one or two normal ringing sessions, especially if you familiarise yourself with using the sensor in advance.

These instructions should be enough to allow you to make the required measurements. Additional documentation is at https://www.dracal.com/store/support/qtenki_howto/index.php. It is assumed that the person carrying out the monitoring will have a reasonable understanding of basic procedures using Microsoft Windows and of any software used to process the results (e.g. Microsoft Excel, Open Office Calc).

Download and install the free Qtenki software This can be done before you have the sensor. It can be downloaded from https://www.dracal.com/store/support/downloads/index.php. As this is not in widespread use, some virus protection programs treat it with caution. You might need to consult your virus protection documentation to find out the additional steps needed to allow it to be downloaded or installed.

Connect the sensor using a free USB socket, and then start Qtenki. If Qtenki was running before the sensor was connected, close it and start it again.

Minimum/Maximum

Go to the Sources tab.

The minimum/maximum value for each source can be seen in the appropriate columns. There is a Reset button on each row, which will clear the existing values.

Current values

Go to the Sources tab.

The current value for each of the three sources can be seen in the appropriate column.

For a clearer view, select the Big View option next to the sources to be displayed, then go to the Big View tab.

Settings on the Configuration tab allow the source name and units to be shown on the Big View.

Real Time Graph

Go to the Sources tab.

Select the Graph option next to the sources to be shown, then go to the Graph tab.

Set the sample interval in milliseconds

Select the Auto-scale options for both axes. This keeps all of the output on the screen, and initially makes it easier to see what is being recorded. You might want to deselect the auto-scale on the x-axis once data is being displayed.

Select the Logarithmic Y axis option if showing multiple values which are likely to have a considerable difference in values (eg CO2 and temperature).

There is an option to save an image of the graph, which can be useful to give an overview of the results. For more detailed later analysis, it is better to use the logging option and create charts from the output.

Logging

Go the the Logging tab.

Select the sources to include. Each will appear in a separate column in the output.

Set up the output file options in the Output Configuration area. If you intend to use a spreadsheet to process the results, then a comma-separated or tab-separated file is recommended ('csv' or 'tsv' formats). If you expect to record more than one set of results, consider, then check that you have not set the output to overwrite a previous file without warning.

If you are keeping a separate log file for each scenario, ensure that the are named so that you can identify which is which. If using a single log file, keep a note of the times of each test, then manually split or annotate the file later.

Set a logging interval in seconds. 10-second intervals will be enough for most scenarios.

Use the buttons in the Control are to start and stop logging.

Use the View File option to check that the file is being recorded as expected.

Including calculated values

Go to the Sources tab.

Calculations are set up in the Math area. There is a row for each calculation.

Click the Help button for full details of the equations that can be created.

Once created, the results can be output in the same way as the original sources.

The number of calculated values available can be set by the Change number of math channels setting on the Configuration tab.

Other useful settings

Aliases

On the sources tab you can enter an alias name for any source or calculation. These will then appear in the output in place of the full name (e.g. 'CO2 ppm' instead of 'E16708:00 -- CO2 Gas PPM')

Decimal Places

The number of decimal places shown is set on the Configuration tab.

Temperature unit

Change from Celsius to Fahrenheit using the Set temperature unit setting on the Configuration tab.

Carrying out tests

Read the paper Carbon Dioxide Monitoring Whilst Ringing and linked items.

For the purposes of ventilation monitoring, it is only necessary to record a log file with the CO2 concentration, but it might be useful to also display the current values or graph during monitoring.

Set up the equipment in plenty of time. Connect the sensor using a USB extension cable if it helps to place it in the required position (5 – 6 feet above floor level, in an area or areas which represents where ringers will be standing).

The sensor available from the DCCR will be supplied with a 3m USB extension. This has a clip and Velcro strap attached to help with mounting the sensor is a suitable position.

Pragmatic Testing

Plan the scenarios during which montoring will be carried out.

Combinations of bells to ring
How many windows to be open
Whether fans will be in use
Include a measurement of the CO2 outside the tower.

Measuring Air Changes per Hour

This will require the CO2 levels in the room to be artificially raised, and the time taken for it to return to normal recorded. Be aware of the risks detailed in the CC doc. Also read the information from the HSE at https://www.hse.gov.uk/carboncapture/carbondioxide.htm

Bear in mind that, as CO2 is heavier than air, the tower stairs might also be subject to dangerous levels.

Results

Ensure that you document the tests carried out. Include details such as the dimensions of the ringing room and windows, number of people present (including any not ringing), and ventilation arrangements.

Please share you results with the CC. An email address for Dr David Pouncey in included in the CC paper.

Page updated

Google Sites

Report abuse