The APM-2 panel utilizes STAHL Model 9251/02 dual channel intrinsically safe repeater relays, which are UL, FM and CSA approved for intrinsically safe connection in Class I, II and III, Division 1 and 2, Groups A - G hazardous locations. The 8.2 VDC intrinsically safe sensing circuit, of the STAHL 9251/02, safely interfaces the annunciator panel with the normally closed reed switches, which are located in a hazardous location. The UL approved independently operating reed switches are float activated to open at 95% of tank capacity representing HIGH LEVEL ALARM condition and at approximately 98% of tank capacity representing OVERFILL ALARM condition. Each cargo tank is fitted with the aforementioned sensors (switches).

    Outwardly, the panel annunciator light layout reflects the cargo compartment configuration with an amber and red light pair representing HIGH LEVEL ALARM and OVERFILL ALARM respectively for each cargo compartment. Additionally, amber High Level Alarm and red Overfill Alarm 2,000,000 C.P. strobe lights sit atop the panel. The front mounted audible alarms for both High Level and Overfill have a continuously rated sound level of 105 D.B. at 1 meter. An on/off rotary switch with power "on" light, battery condition voltmeter and red low power warning light are also located on the front of the panel.