Apollo 55000-450APO XP95A 135°F Heat Detector

The Apollo 55000-450APO XP95A Heat Detector provides intelligent addressable thermal detection for compatible Apollo XP95A fire alarm systems. It uses a single thermistor to continuously monitor surrounding air temperature and transmit an analog value proportional to the detected temperature back to the fire alarm control equipment.

Its addressable design provides individual point identification for professional commercial and institutional fire alarm applications.

135°F Intelligent Heat Detection

The thermistor produces an output proportional to external air temperature, which is converted into an analog value and transmitted to the compatible control panel. Apollo specifies that an analog count of 55 corresponds to the UL alarm sensitivity level of 135°F.

Important product detail: Apollo’s official documentation for 55000-450APO does not identify this model as a rate-of-rise detector. It is documented as the XP95A Heat Detector (135°F) using proportional thermistor temperature sensing. The separate Discovery UL heat detector family offers multiple operating modes.

Key Features

• XP95A intelligent addressable heat detector
• 135°F (57°C) alarm level
• Single thermistor electronic sensing
• 17–28 VDC operating range
• Low 250 µA supervisory current
• Individual addressable point identification

Electrical and Physical Specifications

The Apollo 55000-450APO operates from 17 to 28 VDC and uses a 5–9 V peak-to-peak protocol voltage. Apollo specifies a supervisory current of approximately 250 µA, a surge current of 1 mA, and maximum alarm current of approximately 2.5 mA with the LED illuminated.

The detector has a white polycarbonate housing approximately 3.94 inches (100 mm) in diameter and operates across an ambient temperature range of approximately 32°F to 151°F (0°C to 66°C).

XP95A Detector Design

Apollo identifies the original 55000-450APO as obsolete and lists the newer SA5500-450APO XP95A Heat Detector as its replacement. The newer detector remains backward compatible with legacy XP95A systems.

55000-450APO Datasheet