Moving surface disinfection from the laboratory to a production conveyor is rarely as simple as selecting a lamp and installing it above the belt. The final result depends on irradiance, exposure time, distance to the product, lamp arrangement, surface geometry, and the susceptibility of the target microorganisms.
A large industrial company in Irkutsk needed a compact conveyor UVC system for laboratory experiments. The objective was to study the treatment of moving samples and collect enough data to design a larger production-scale installation.
The Experimental Task
The planned test rig had to process small film samples measuring approximately 50 × 50 mm. The conveyor needed enough usable width to arrange the samples in two parallel rows.
The system also had to support experiments with several variables:
conveyor speed;
distance between the lamps and samples;
number of UVC lamps;
lamp arrangement;
number of passes through the treatment zone;
different materials and surface properties.
The customer initially considered a housing approximately 200 mm wide. More importantly, the mechanical design had to allow the optical configuration to be changed without manufacturing a new enclosure for every experiment.
Why Lamp Count Is Not the Only Variable
Adding more lamps generally increases the available UVC power, but lamp count alone does not determine the dose received by the surface.
For a moving sample, the approximate exposure time can be calculated as:
where:
(t) is the exposure time;
(L) is the effective irradiated length;
(v) is the conveyor speed.
The surface dose can then be estimated as:
D = E_{\text{avg}} \times t
where:
(D) is the UVC dose;
(E_{\text{avg}}) is the average irradiance across the treated area.
In a real conveyor system, irradiance is not perfectly uniform. It changes with the distance from the lamp, reflector geometry, neighbouring lamps, housing dimensions, and the position of the sample on the belt. This is why the minimum measured irradiance across the working area may be more useful than a single peak value recorded directly below a lamp.
Selecting the Base Configuration
For the first stage, the customer selected the compact VOZUF-410 conveyor irradiator.
The base configuration included:
a 410 mm stainless-steel housing;
one UVL 1980 low-pressure germicidal lamp;
electrical lamp power of 80 W;
germicidal output of approximately 25 W;
dominant emission near 254 nm;
an electronic ballast and connection components.
A single-lamp version provided a practical baseline. It allowed the engineering team to measure the irradiance distribution, establish an initial exposure window, and evaluate the response of different samples before increasing the system’s complexity.
Comparing Two- and Three-Lamp Layouts
After the initial configuration was selected, two-lamp and three-lamp versions were also considered.
A two-lamp layout can increase the treated width and improve uniformity when the lamps are positioned symmetrically above the conveyor. A three-lamp arrangement provides additional design options, including a triangular layout in which the lamps illuminate the working area from different angles.
However, a triangular configuration does not automatically produce a higher useful dose at every point. Its performance depends on:
lamp spacing;
distance from each lamp to the conveyor;
reflector shape;
shadowing caused by holders and structural elements;
angular response of the measuring instrument;
reflectivity and geometry of the samples.
The configurations therefore need to be compared using irradiance measurements at multiple points across the belt. A grid measurement or UVC-sensitive film can reveal both the average intensity and low-dose zones that may otherwise remain unnoticed.
Designing for Modification
The experimental enclosure was designed around a consistent mechanical platform. This allowed the number and arrangement of lamps to be changed while retaining the main housing.
Drawings, ballast connection diagrams, and mounting information were prepared for the customer. This modular approach offered several advantages:
one housing could support multiple experimental configurations;
lamp layouts could be compared under similar mechanical conditions;
modifications required fewer custom parts;
the resulting data could be used to define a production-scale system.
Electrical compatibility still had to be checked for every configuration. The ballast, lamp current, wiring diagram, connectors, cooling conditions, and switching components must match the selected lamps. Additional lamps should not simply be connected to an existing single-lamp ballast unless the ballast is specifically designed for that load.
A Practical Test Method
A useful experimental programme can be divided into four stages.
- Map the Irradiance
Measure the UVC irradiance at several points across the conveyor width and along the effective treatment zone. Record the lamp-to-sample distance and allow the lamps to reach stable operating conditions before taking measurements.
- Establish the Exposure Matrix
Run samples at several conveyor speeds. If necessary, repeat the test at different lamp heights and with one-, two-, and three-lamp configurations.
- Perform Microbiological Validation
Irradiance measurements describe the physical exposure, but they do not prove a specific disinfection result. Representative microorganisms and real product materials should be tested using a defined sampling and cultivation method.
- Account for Operating Degradation
A production system should not be sized only from measurements taken with clean, new lamps. Lamp ageing, dust, surface contamination, temperature, reflector condition, and voltage variation can reduce the delivered dose. An appropriate engineering margin should be included when scaling the system.
Safety Requirements
Short-wave UVC radiation can injure the eyes and skin. A laboratory conveyor irradiator should therefore operate as an enclosed or guarded system.
A safe installation may include:
opaque shielding around the exposure chamber;
interlocked access panels;
a clearly marked emergency stop;
remote switching;
warning indicators;
protection against direct and reflected UVC exposure;
procedures for safe lamp replacement and maintenance.
The safety design becomes especially important during experiments because lamp positions and protective panels may be changed more frequently than in normal production equipment.
From Laboratory Data to a Production Line
The laboratory unit was supplied shortly after the order was confirmed, allowing the customer to begin testing without committing to a full-scale installation.
The main value of the project was not the compact irradiator alone. It was the creation of a controlled platform for answering the questions that matter before scale-up:
What dose is required for the target microorganisms?
Which conveyor speed provides sufficient exposure?
How uniform is the treatment across two rows of samples?
Does an additional lamp improve the minimum dose?
Which geometry offers the best balance between performance, size, and energy consumption?
Once these values are measured, a production system can be designed from experimental evidence rather than nominal lamp power alone.
Conclusion
A modular conveyor UVC rig is an effective way to evaluate surface-treatment processes before installing equipment on a production line. Starting with a single-lamp system creates a reference point, while two- and three-lamp configurations make it possible to study dose uniformity and scaling behaviour.
The critical step is to treat the project as an experiment: control the geometry, measure irradiance, validate the microbiological result, and document every operating parameter. This produces data that can be transferred to a larger conveyor with substantially less technical uncertainty.
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