Product Handbook 2026 - Volume 1

Boiler house Level controls

2

Local regulations may restrict the use of this product to below the conditions quoted. In the interests of development and improvement of the product, we reserve the right to change the specification without notice. © Copyright 2020

TI-P693-28 EMM Issue 1

PA420 Preamplifier

Description The PA420 preamplifier, used with a Spirax Sarco capacitance probe, is a loop powered two wire 4 - 20 mA level transmitter. It amplifies the capacitance measured and converts it to a 4 - 20 mA output proportional to the liquid level. It is compatible with all Spirax Sarco current input controllers/transmitters. The preamplifier consists of a tubular austenitic stainless steel body which screws onto the top of the probe, and has a Type A EN 175301-803 (DIN 43650)/ISO 4400 connector with Pg 11 cable gland. The PA420 has two buttons and a dual coloured light (red and green) for use during commissioning. Principal features: - Compact, rigidly mounted. - Can be removed/replaced without disturbing the probe. - No maintenance needed. - Suitable for all probe lengths (370 - 1 500 mm). Approvals: - TÜV, VdTÜV-Merkblatt, Wasserstand 100 - 2017. - Electromagnetic Compatibility Directive 2014/30/EU. Caution: The probe is not suitable for outside installation without additional environmental protection.

Materials

2.3 113

2

3

1

4

No Part

Material

1

Body

Austenitic stainless steel 300 series

2

Cable connector Polyamide (Glass filled)

Limiting conditions Ambient temperature range

3

Connector gasket Silicone rubber

0 - 70 °C

4

'O' ring

Nitrile rubber

Pollution degree

3

Water conductivity

5 µS / cm or 5 ppm

Maximum cable length

100 m (screened)

Technical data Voltage drop (across the device)

9 - 26.4 Vdc

Loop current

4 - 20 mA

Maximum load

500 Ω

Linearity

2% FSD

Isolation

100 Vdc (capacitive)

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