Constraints, Measurement, and Maintenance 9/19/2018 UVGI: Constraints, Measurement, and Maintenance Sonya Milonova Research Fellow Harvard School of Public Health July 9, 2015

Constraints Measurement Maintenance

Constraints High humidity thought to protect organisms 9/19/2018 Constraints High humidity thought to protect organisms Requires vertical air mixing Low ceilings Lack of guidelines, as well as education on proper dosing, installation, maintenance, etc. Access to well designed fixtures Meters (expensive and unavailable)

Constraints Measurement Maintenance

Measurement: Definitions 9/19/2018 Measurement: Definitions Irradiance UV energy flux reaching a flat surface Units: watts/square centimeter (W/cm2) Important in the lower room Fluence rate UV energy flux reaching a tiny spherical surface Important in the upper room Fluence: energy delivered per unit area

Measurement: Inverse Square Law Describes the relationship between irradiance from a point source and distance

Measurement: Radiometers 9/19/2018 Measurement: Radiometers Hand-Held Meters International Lighting ( $1500) Gigahertz-Optik Flat sensor ( $2500)

Measurement Calibration 9/19/2018 Measurement Calibration Periodic (every 3-4 years) comparison against calibrated meter Zero adjustment Potential interferences Fluorescent lights Sunlight (even through windows)

Measurement Lower room: 9/19/2018 Measurement Lower room: Measurements in lower room (approx. 1.8 m from the floor) should not exceed a total dose of 6.0 mJ/cm2 over an 8 hour work day Check places where occupants will spend most of their time (ie. beds in hospital ward) Upper room: Measurements above fixtures (2.4 m and above) should be as high as possible while maintaining safe lower room levels Keep sensor horizontal (parallel to earth) Swivel sensor 360° to find maximum reading

Measurement: 80° FOV tube Threshold Limit Value specifies that the source needs to be measured over an angle of 80 degrees at the detector Use a Field of View (FOV) tube attached to a UVC sensor for lower room safety measurements Tests indicate the sleeve would reduce lower room measurements by 5-45% (depending on location)

Constraints Measurement Maintenance

Maintenance Establish realistic maintenance and operation objectives during the design phase of the UVGI installation Tasks: Output measurements Fixture and lamp cleaning Routine inspections of fixture installations Repairs Important considerations: Documentation Communication

Emission Performance Initial decline during break-in period Gradual decline over lifetime due to lamp solarization (frosting) and metal deposition on inner surface Lamp failure: Even if UV is hardly being emitted, might see blue light

Emission Performance Annual lamp emission decline observed: 9/19/2018 Emission Performance Annual lamp emission decline observed: Average 16% decline for linear tube lamps Average 26% decline for folded (compact) lamps Annual lamp failure observed (~9000 hours): <1% for linear tube lamps <2% for folded lamps Continuous operation can extend reported lifetime by up to 60%

Emission Performance After the fixture has been on for 100 hours, measure the baseline output: Stand 1 m away, directly in front of center of fixture Measure at height of fixture (use tripod) Keep sensor horizontal (parallel to floor) Direct sensor straight forward (toward fixture) Find maximum Record baseline output in logbook Repeat every 6 months Replace lamp when output = 70% of baseline After the fixture has been on for 100 hours, measure the baseline output: Stand 1 m away, directly in front of center of fixture Measure at height of fixture (use tripod) Keep sensor horizontal (parallel to floor) Direct sensor straight forward (toward fixture) Find maximum Record baseline output in logbook Repeat every 6 months Replace lamp when output = 70% of baseline

Lamp Cleaning Frequency of cleaning is site specific: 3 month cleaning intervals for dusty, active areas Annual cleaning intervals for most other areas Clean lamps and reflective surfaces with gauze and cleaner containing 70% (or more) alcohol Avoid touching the bare lamp with your hands Use a multi-stranded polymer brush to clean between louvers

Inspections Initial inspection: Level with the earth? Properly fixed to the wall/ceiling? Pointing in the right direction? Mounted high enough? Routine inspection: Is the lamp turned on? Is it clean? Check maintenance log

Fixture Repair Establish defined, comprehensive replacement and repair agreement with vendors Keep track of warranties Receive advance replacements and use packaging for return and repair of defective or damaged fixtures

Communication Establish communication responsibilities If a lamp burnout (or other problem) is observed, who notifies facility maintenance? Once initiated, who is responsible for inspecting/ replacing the lamp? If the individual responsible leaves the facility, how is the communication process altered? UVGI maintenance and repair procedures should be incorporated into existing facility maintenance procedures

Cost of Maintenance Supplies/Equipment Cleaning supplies (gauze, alcohol, brushes, etc.) Replacement lamps and parts Replacement of worn out or defective fixtures, including handling and shipping costs Labor Routine labor: fixture maintenance incorporated into routine physical labor; and/or Dedicated labor: quarterly or annual maintenance tasks with labor per fixture established and budgeted

Maintenance Re-Cap Maintenance strategies begin at the initial purchase of UVGI fixtures Identify individuals responsible for maintenance Replace lamps on rotating schedule; focus cleaning efforts on target zones Keep clear maintenance logs and formally pass UV system maintenance responsibilities to new staff Utilize the resources of the upper room UVGI research community to continue learning about UVGI research and operating experience

Coming Soon… UVGI Disinfection of Room Air: An Evidence Based Guideline for Design, Implementation, and Maintenance Specific for South Africa Includes guidelines for UVGI dosing, fixture design, installation, verification testing, monitoring and maintenance, and much more!

Questions? Special thanks to: Thomas S. Dumyahn