Refrigerating appliances live in harsh, real-world conditions: ambient humidity fluctuates, frost builds on evaporators, and each defrost cycle generates water that must be safely routed and evaporated. IEC 60335-2-24 the particular safety standard for refrigerating appliances, ice-cream appliances, and ice-makers—addresses these realities with a series of type tests. Among them, the apparatus for water evaporation and for accumulation of frost plays a central role in verifying that an appliance manages frost and defrost water without introducing hazards or functional failures over its service life.

This article explains the engineering intent behind that apparatus, how we at Wewon design and qualify compliant rigs, and what manufacturers should look for when planning certification or internal validation. It is written for engineers, quality teams, and lab managers who need a practical, audit-ready approach that aligns with IEC 60335-2-24 Clause 11 and Annex BB Figure BB.1 without quoting the standard verbatim or revealing controlled content.

The accumulation of frost may be produced by the use of a device having a controllable heat source directed on a measured amount of water for the purpose of evaporating this water over a predetermined period with a minimum of extraneous heat loss to the cabinet of the refrigerating appliance.	Method for Accumulation of Frost IEC 60335-2-14
A convenient form of the apparatus would comprise a block enclosure of thermally insulating material having a vertical hole at its centre containing a lamp mounted on a bottom plug directly below an evaporating_ dish with a high thermal conductivity base and low thermal conductivity walls (see Figure BB.1 and Figure BB.2).
The device described above should be mounted at the geometric centre of the cabinet of the refrigerating app/iance and the electrical connection brought conveniently to the outside so that the voltage applied may be varied and the power input measured with the door of the refrigerating appliance in the closed position.
Water is then introduced into the evaporating dish at the required rate through a length of small bore tube passing into the cabinet. A continuous flow is not necessary but the water should be injected at appropriate intervals.
Provision should be made (for example in the control of the supply of electrical energy to the device) to ensure that the evaporation of water under normal conditions of use is capable of being maintained at a rate equal to 2 g of water per litre of gross cabinet volume per week.
The electrical energy to the device should not be excessive, but shall be sufficient to ensure the complete evaporation of the water.
The amount of frost to be accumulated prior to the stad of the defrosting test should be based on this rate and on the time interval between two successive defrosts in accordance with the instructions.
Note, For example,if the instructions recommend defrosting twice weekly, then a refrigerating appliance with a cabinet gross volume of 140 I will require: 2g· 140/2 = 140 g of water
The above rate may be exceeded in certain circumstances. The apparatus described has a maximum evaporation rate of approximately 2 g/h when operating with an input of 4 W and with the water to be evaporated entering at cabinet temperature.
Figure BB.1 – Diagram of apparatus for water evaporation and for accumulation of frost
Figure BB.2 – Apparatus with lamp for water evaporation and for accumulation of frost
Figure BB.2 – Apparatus for water evaporation and for accumulation of frost

●	What is the purpose of the apparatus for water evaporation and for accumulation of frost in IEC 60335-2-24? Answer: It verifies that a refrigerating appliance accumulates frost realistically, defrosts effectively, and safely evaporates the resulting water—without overflow or hazardous leakage—under standardized conditions.
●	How does IEC 60335-2-24 Clause 11 and Annex BB Figure BB.1 guide the test? Answer: Clause 11 frames thermal and operational aspects for safety, while Annex BB (with Figure BB.1) illustrates the apparatus and methods for frost accumulation and water evaporation so results are comparable across labs.
●	What instrumentation is essential? Answer: Temperature (Pt100 or thermocouples), humidity, mass/volume for meltwater, airflow (where required), and synchronized timing. A defrosting test apparatus with digital display simplifies visualization and record-keeping.
●	Can I use a generic humidity chamber instead? Answer: Only if it can replicate the Annex BB spray/atomization geometry and control points. Many teams still require the dedicated accumulation of frost defrosting test apparatus to ensure fidelity.
●	How do I size the defrost pan? Answer: Estimate the worst-case meltwater mass per defrost, add safety margin, and verify with the water evaporation defrosting test apparatus under controlled heat input and airflow.
●	What’s the most frequent failure you see? Answer: Overflow due to marginal pan volume or insufficient heating, especially in humid ambients. Drain path restrictions are a close second.
●	Does the apparatus help with energy optimization? Answer: Yes. By logging evaporation time versus heater power and airflow, you can find the lowest energy configuration that still complies.

Equipment Model: WEW-WEAF-IEC-60335	Heat Source: 5W Incandescent
Equipment Name: Apparatus for Water Evaporation and For Accumulation of Frost	Output Voltage: 5-220V Adjustable
Test Standard: IEC 60335-2-24	Display Method: Digital Display
Power Supply: Match Client’s Local Power Supply	Weighing Mode: Weighing Mode of Consumed Water: Digital Display Electronic Balance
Enclosure Material: PVC or Bakelite	Injection Modes: Manual Injection
Thermal Plate Material: Red Copper Plate	Figure BB.2 Apparatus for Water Evaporation and for Accumulation of Frost

In normal operation, frost accumulates on cold surfaces (e.g., the evaporator). Periodically, appliances defrost—either automatically (electric heater, hot-gas, or off-cycle) or manually. That meltwater is channeled to a pan for disposal, typically via evaporation using compressor waste heat or a dedicated heater. If frost builds too aggressively, defrost is ineffective, water overflows, or liquid contacts live components, safety and performance are at risk.		1) Why Annex BB Exists and What It Proves
The accumulation of frost and water evaporation apparatuses specified around IEC 60335-2-24 Annex BB Figure BB.1 provide a uniform way to:
* Generate and control frost growth on the appliance (or a representative heat-exchange surface).
* Trigger a representative defrost event and collect the resulting meltwater.
* Verify that the appliance’s construction (drainage, pan size, pan heating, airflow) evaporates the expected quantity of water within the required time and without overflow or leakage.
Engineers rely on these tests to balance design trade-offs: pan volume versus footprint, heater power versus energy consumption, drain path geometry versus manufacturability, and evaporator fin spacing versus airflow and icing propensity.
While each lab’s implementation varies, a compliant defrosting test apparatus includes two coordinated modules:	1. Accumulation of Frost Module	2) What the Apparatus Looks Like (High-Level Overview)
* Controlled ambient (temperature and humidity) and airflow to promote repeatable icing on the appliance’s evaporator or designated surface.
* Spray, atomization, or humidification fixtures configured as illustrated in IEC 60335-2-24 Annex BB Figure BB.1, ensuring uniform wetting and frost deposition consistent with the standard’s intent.
* Instrumentation to log surface temperatures, ambient parameters, and time to frost thickness/mass criteria.
* A drain-path capture fixture that routes meltwater to the appliance’s defrost pan (or a representative pan with equivalent thermal coupling).	2. Water Evaporation Module
* Weighing or volumetric measurement to quantify collected meltwater.
* A controlled heat source (e.g., compressor simulator or heater element) delivering a known thermal input to the pan, aligned with the appliance’s real defrost/operation profile.
* Timers and data logging to confirm the water fully evaporates within the allowable window and that no overflow or leakage occurs at any stage.
At Wewon Environmental Chambers Co., Ltd. , our integrated defrosting test apparatus with digital display combines these modules in one frame, so technicians can set environmental profiles, track sensor readings, and export compliance datasets without juggling multiple instruments.
In the IEC 60335-2-24 Clause 11 addresses heating and thermal aspects under normal operation and test conditions. For Part 2-24, those provisions adapt to refrigerating appliances—capturing how heat sources (e.g., compressor shell, defrost heaters, pan heaters) interact with water management. In practice, your test plan will cite IEC 60335-2-24 Clause 11 and Annex BB Figure BB.1 when you:	3) Where Clause 11 Fits
* Demonstrate that frost accumulation is representative of real use.
* Confirm defrosting effectiveness and water handling is safe, controlled, and repeatable.
* Show that the water evaporation defrosting test apparatus validates pan capacity, thermal input, and evaporation rate in a way that is traceable and auditable.

When refrigerators and ice-making appliances run in real homes or retail spaces, two things are guaranteed to happen: frost forms, and defrost water needs to be managed safely. IEC 60335-2-24 the particular safety standard for refrigerating appliances – addresses both phenomena with defined type tests. At the center of those tests is an apparatus for water evaporation and for accumulation of frost that creates repeatable, evidence-based conditions to verify an appliance’s design choices.

Why an Apparatus for Water Evaporation and for Accumulation of Frost Is Essential ? Frost accumulation affects airflow, heat exchange, and energy consumption. During defrost, meltwater must drain to a pan and evaporate before it can overflow, refreeze, or migrate to live parts. If any link in this chain is weak – drain geometry, pan size, heater power, or airflow – safety and reliability suffer.

Refrigeration safety testing deals with cold surfaces, water, and electricity in close quarters – meaning safety discipline is non-negotiable. Enforce the notices above, follow the rating on the nameplate, keep your apparatus clean and calibrated, and store complete records for each test run. When in doubt, talk to our technical support team; we are here to help you convert Annex BB requirements into crisp, repeatable engineering evidence.

If you are planning to implement, upgrade, or audit a water evaporation and accumulation of frost setup for IEC 60335-2-24, share your product category, defrost method, and target throughput with us. We’ll recommend a right-sized configuration – spray manifolds, thermal coupling, sensors, and a defrosting test apparatus with digital display that accelerates your path to compliant, dependable refrigeration products.

The following instructions are included verbatim for clarity and to ensure safe operation in your laboratory. Please review and enforce them in your SOPs.		Maintenance Notice:
Properly adjust the voltage value within the range (20 – 220V).	Attention Matters
Make sure to cut off the power supply and unplug the power plug before performing routine maintenance of the instrument, such as cleaning or replacing the fuse. The internal cleaning and fault repair of the instrument must be performed by professionals. It is forbidden to open the case at ordinary times to avoid electric shock, burns and other accidents.
Do not use this product in a corrosive environment. Do not use this product in places containing corrosive liquid or gas.	Operation Notice:
Do not operate in an explosive environment. Do not use this product where flammable and explosive materials are placed.
Before turning on the power, please ensure the product is well grounded, and avoid using the neutral wire as a protective ground wire.	Ground Protection
Before turning on the power, make sure that the voltage of the power supply matches the	Power Supply
The power supply should be AC220V±10%, 50/60Hz.	Rated Voltage
Always follow the rating on the instrument nameplate. If local mains are outside the specified tolerance, use a regulated transformer or consult our team before operation.