5 things about Baseline Report that no LEV and GV system installers will tell you about.
Every single time when it comes to LEV and GV system assessment, you may have various versions of criterion or recommended limits used by the Industrial Hygiene Technician Registered with JKKP to complete their assessment. For example, a fume hood capture velocity recommended limit which would be taken from its face opening can vary from 40, 60, 80, 100, 125, and up to 200 fpm. There are technicians who strictly follow their training notes and will be adamant about their selection of numbers in evaluating the assessment, keeping it at 100 to 200fpm. There are several consensus, perceptions, and interpretations based on their individual level of experiences. However, the big question is, are Industrial Hygiene Technicians 2 (IHT2) registered with JKKP suppose to set the criterion for assessment, in the very first place?
This is why you need to read about these 5 things no system installer will tell you about the ventilation system baseline report. Why system installer won’t tell you? They don’t because most of the time they themselves don’t understand the requirement of the Regulations and the project management practices highlighted in the ACGIH Design Manual for Ventilation Systems. Furthermore, it has always been a practice to ‘guestimate’ the sizing of the ventilation system based on past experience in sizing fans and ducts rather than using an effective way of calculating flow rate from capture velocity and air change per hour.
Number One - Define the objective of the ventilation project is met.
Upon physical installation of a ventilation system, the powered-up system will undergo several balancing works with preliminary testing to set the system to meet its design numbers. During these exercises, if the preliminary numbers are not inadequate, corrective action will need to be taken until the design numbers can be met.
A baseline report is the final version of a commissioning report, being established to depict the peak performance of the system that meets the design criterion. The design criterion here is a parameter chosen by the designer such as capture velocity, air change per hour, and direct flow rate as per the machinery manufacturer’s recommendations. At this point, one must really understand that it is not the duty of the hygiene technician to set the criterion but he or she is to follow what was set in the design template. Picking a criterion as per their own interpretation without studying the design template and baseline report is a cardinal error in conducting LEV and GV system performance assessments. The baseline report confirms if the design objectives are met via velocity and air concentration results.
Number two - establishing an actual criterion for future periodic assessment.
The baseline report is the actual performance proof of the system meeting design numbers simulated by the designer. Its performance is to fall under the range of criteria set in the design templates. The actual numbers will need to be met by conducting air balancing such as damper adjustment, and fan speed adjustments. Once these numbers are met, it will become the criterion that is to be maintained within the range of peak and lower limit of the design criterion. For example, the lower limit for fume hood capture velocity can be 40 fpm or 60 fpm depending on the make-up air and traffic condition in front of the hood.
Number three - a compilation of important design documents as proof of commissioning.
A baseline report has its primary objective of meeting the design specification and establishing baseline data. The design specification and design drawing will become its criterion to be validated based on on-site construction and measurement results. Once the numbers meet the design specification under the similar design routing, the as-built drawings will be used as proof of validation and to be used in depicting the baseline assessment point locations. Other important documents such as the fan-system performance curve and preventive maintenance/performance monitoring checklist must also be attached to the baseline report so that these compilations can also kick start the engineering change of management protocol to be adopted in managing the system.
Number four - provide references and numbers for future changes or upgrades.
Baseline reports allow the implementation of engineering change in management. The goal of engineering change management is to support the processing and traceability of changes to an interconnected set of factors related to the engineering control systems. For instance, In the event a new branch is added, a design document alone will not enable the feasibility of the addition. The actual peak performance compared to air balancing settings such as damper closure or optimized fan speed need to be used in simulating the new changes in the system’s flow rate and static pressure demand. None of these will be feasible without any baseline report.
Number Five - The most important reference needed for the system’s troubleshooting.
If a flow rate of a system drops at the hood, the baseline speed of the fan is the first parameter that needs to be cross-checked for the troubleshooting measures. By referring to the fan curve for the rated speed, the current speed can be tested if there is a drop. A drop in fan speed can easily occur if there are problems with the bearings, imbalance impellers, misaligned shaft, loose v-belts and etc. If the speed is good, next up is to check the ducting system’s static pressure distribution. Any resistance increase across the ducting will elevate the system static pressure making the overall flow rate dwindle. Examples of resistance increase will be filter clogging, elbow clogging, and constriction of passages along a segment of a duct.
Now, with this additional understanding of the engineering control system baseline report, make the entire periodic assessment and preventive maintenance protocol to be a much more effective one.