Spirax Sarco LP30 - General Product Information; General Description; Technical Data

IM-P402-44 AB Issue 15
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2.1 General description
The Spirax Sarco LP30 level probe is used with the Spirax Sarco LC3050 level controller to
provide a high integrity, self-monitoring low level alarm signal, usually in a steam boiler. It
consists of a probe body with a removable cable socket, and a separate screw-on probe
tip. The tip is retained with a roll pin, and held in place with a lock-nut. Two level probes and
controllers are normally installed on each boiler to provide two independent low alarms. In
many countries this provides first low alarm and second low alarm. The probe is suitable for
boiler pressures of up to 32 bar g (464 psi g).
2.2 Available tip lengths mm(inches)
500 (19.7), 1 000 (39.4) and 1 500 (59).
2.3 Pressure / temperature limits
Nominal pressure rating PN40
Maximum boiler pressure 32 bar g (464 psi g)
Maximum operating temperature 239°C (462°F)
Maximum ambient temperature 70°C (158°F)
Designed for a maximum cold hydraulic test pressure of: 60 bar g (870 psi g)
2.4 Technical data
Maximum probe cable length 50 metres (164 ft)
2.5 How the LP30 works
The probe has a level sensing tip (probe tip) and a comparator tip. The earth return path is via
the body connection.
Under normal operating conditions, the probe tip is immersed, and the resistance to earth is
low. When the water level drops below the probe tip the resistance to earth becomes high,
causing the controller to give a low level alarm signal.
The comparator tip compensates for any leakage to earth caused by scale, dirt, or internal
moisture, ensuring a low water alarm signal even under adverse conditions.
A DIN 43650 cable socket is supplied with each unit and is provided with a Pg 11 cable gland,
or, for the UL/FM version, a ½" NPT conduit thread adaptor with four flying leads.
WARNING: It is essential that the probe tip does not touch any part of the boiler.
Standards require that the tip is at least 14 mm ( ") from the protection tube, and
this must be checked when the probe is installed. See Section 5, 'Probe clearance
test procedure'.
2. General product information