Page 10-8
Pilot’s Operating Manual
Revision A2: Nov, 2004
Sub-section 10
ENVIRONMENTAL
Hawker 800XP Pro Line 21
Section III - SYSTEMS DESCRIPTION
LOW LIMIT TEMPERATURE CONTROL SYSTEM
The air temperature at the inlet to the water separator is limited by a control circuit to a minimum
temperature of about 2
°
C to prevent freezing and subsequent blockage of the water separator. Warm
air is routed from the primary heat exchanger outlet via the Low Limit Temperature Control Valve
(LLTCV) to the inlet of the water separator.
NOTE:
In extremely cold conditions the temperature at the inlet may drop as low as -8
°
C when cabin
temp is set to max cool (auto or manual).
In the unlikely event that freezing would occur at the water separator due to high humidity at
these cold temperatures, the bypass valve in the water separator would open and allow
continued flow.
The operation of the LLTCV is controlled by a low limit control sensor in the duct downstream of the
water separator. The low limit temperature control system operates independently of any other system
and can override cold selections made by the flight crew.
DUCT TEMPERATURE
A DUCT TEMP indicator is connected to a temperature sensor located in the duct downstream of the
silencer. This temperature may be considered as the cabin air inlet temperature.
Should the temperature be exceeded, a duct over temperature sensor, set at 115
°
C, will cause a DUCT
OVHT amber repeater annunciator to illuminate on the MWS panel, which draws attention to the DUCT
TEMP indicator located on the overhead roof panel.
The over temperature signal will also cause the cabin temperature control valve to be motored fully
closed. When the temperature in the duct falls, normal automatic control is restored and the DUCT
OVHT repeater annunciator extinguishes.
MWS Annunciator Panel
DUCT
°
C
0
+50
100
DUCT
OVHT
DUCT TEMP
Overhead Roof Panel
