IQF freezer defrosting: how often, and how it affects output

In an IQF freezer, frost on the evaporator and belt cannot be avoided. The real questions are how long the freezer runs before it must stop to defrost, and how defrosting affects output over a long shift.

Short answer

GLORY Thermal Jet® IQF freezers run more than 20 hours between defrosts, up to 23 hours with the latest generation. The F-series fluidized bed runs more than 16 hours. The longer the interval, the fewer stops, the more production hours and the steadier the temperature.

1. Why does the evaporator frost up?

Moisture from the product and from air entering at the infeed and outfeed openings freezes as frost on the evaporator and belt. A thick frost layer blocks airflow and reduces heat transfer, so chamber temperature rises and capacity falls.

2. How does defrosting affect production?

• The line stops while defrosting and while the chamber pulls down again.
• Chamber temperature drifts before each defrost, making outlet quality harder to keep stable.
• In a two-shift plant, every mid-shift stop costs output.

3. How GLORY lines extend the time between defrosts

• Air blowing clears frost from the belt during production, without stopping the freezer.
• The hardening conveyor after the glazer holds back free water, so it does not follow the product into the re-freezer, frost the evaporator and damage the belt.
• Belt inlet and outlet openings are treated to limit frosting and loss of cold air.
• The F-series fluidized bed needs no compressed-air system to clear evaporator frost during operation.

4. How long do defrosting and restart take?

The freezer defrosts with hot gas or water. The chamber then pulls down from +28 °C to –36 °C in about 30 minutes from a cold start and about 15 minutes between shifts.

5. Cleaning after the shift

SUS 304 stainless steel enclosure (SUS 316 where needed), a fully draining sloped floor and side corridors with doors give cleaning staff access to every part inside. The M-series mesh belt freezer has automatic clean-in-place (CIP).

Frequently asked questions

Do I need to defrost mid-shift?
More than 20 hours between defrosts covers most of two continuous shifts, so the plant can choose when to defrost. GLORY engineers will calculate it for your product and conditions.

What is the chamber temperature?
–40 to –42 °C, with an evaporating temperature of about –45 °C.

Can I compare with my current line?
Fill in the freezer questionnaire with your current running hours and number of defrosts, and GLORY engineers will propose improvements.