Heat Indicators

Time-temperature indicators and threshold heat indicators monitor heat exposure of temperature-sensitive products and provide an irreversible visual indication of heat exposure.

Time-Temperature Indicators

Time-temperature indicators, or time-temperature integrators, have a temperature profile based on a temperature specification and number of days to end point.  They are chosen by the manufacturer based on the stability of the product being monitored. For example, Temptime’s HEATmarker® Hx indicator (37oC specification temperature) with 9 days to end point would be used for a less stable product while a HEATmarker Hx indicator with 36 days to end point would be used for a more stable product.

HEATmarker is a miniaturized, self-adhesive label that can be applied directly to temperature sensitive products. HEATmarker gradually changes color as heat exposure accumulates.  This gradual color change indicates when the cumulative heat exposure has exceeded a pre-set limit.  This helps ensure that temperature-sensitive products are used before the indicator reaches its end point, and are discarded once endpoint has been reached.

HEATMarker Specification Temp Days to End Point
Hu 25oC 14, 28, 41
Hx HEATmarker Hx36 37oC 9, 12, 18, 24, 36
M 8oC 8
H 8oC  21
E 60oC 30

More HEATmarker information

HEATmarker VVM
Vaccine Vial Monitors

HEATmarker VVM is a label containing a heat-sensitive material that is affixed to a vaccine vial by the drug manufacturer to allow for full-life heat monitoring. Since the HEATmarker VVM and the vaccine move through the supply chain together, they are exposed to the same conditions and MKT. This allows the HEATmarker VVM to give health workers an overview of the cumulative heat exposure of the vaccine and a clear indication when it has reached its time-temperature end point.

HEATmarker VVM Temperature
Days to End Point Shelf Life (years from date of manufacture) Size
High 37oC  30 5 10 mm diameter
Medium 37oC  14 5 10 mm diameter
Moderate 37oC  7 4 10 mm diameter
Least 37oC  2 4 10 mm diameter

More HEATmarker VVM information

Threshold Heat Indicators

LIMITmarker® indicators are characterized by their response temperature and response time.  When LIMITmarker indicators are exposed to temperatures at or above the response temperature, the indicators change color within the specified response time – giving a visual warning that the temperature has been exceeded. For example, a LIMITmarker F-A has a response temperature of 9oC and a response time of 2 hours.  Within 2 hours of exposure at or above 10oC (given accuracy of +/- 1oC), the LIMITmarker F-A indicator will change from white to pink or red.

LIMITmarker is a self-adhesive label that can be applied directly to heat-sensitive products and is available with Delayed Indication (response within 2 hours) or Immediate Indication (response within 15 seconds).

LIMITmarker Response Temp Response Time Accuracy
Delayed Indication
F-A 9oC 2 hours  +/- 1oC
F-B 17.5oC 2 hours  +/- 1oC
F-M 25oC 2 hours  +/- 1oC
F-Y 31oC 2 hours  +/- 1oC
Immediate Indication
I-K 40oC 15 seconds  +/- 1oC
I-P 44oC 15 seconds  +/- 1oC
I-C 50oC 15 seconds  +/- 1oC

More LIMITmarker information

Shipment Temperature Monitors

TransTracker indicators with LIMITmarker heat indicators are single-use devices that can be placed in shipment packaging to monitor heat exposures during shipping.  TransTracker indicators come with detailed instructions for reading the indicator, and may be customized with branding and messaging from the shipper or supplier.

TransTracker Response Temp oC Response Time Accuracy
F  9, 17.5, 25, 31oC  2 hours +/- 1oC
D 40, 44, 50oC  15 seconds  +/- 1oC

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