Severn Trent VAX4600 Series, Instruction Manual

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115.6001.10

1

INTRODUCTION

1.1

General

Process chemicals like chlorine or sulfur dioxide, are available as a liquid, but are normally fed as a gas, and
may be fed directly from their storage container (cylinder or ton container) provided each liquid’s vaporizing
requirements do not exceed the container’s maximum vaporization rate. When large quantities of gaseous
chemical are required, a liquid chemical vaporizer may be used. The vaporizer does not increase or
decrease the pressure of the chemical being vaporized., but changes its state from liquid to gas.

NOTE: The following documents are referenced within this instruction manual:

115.3002 - Vaporizer Piping Connections

115.3003 - Typical manifold Piping for Vaporizers

115.3004 - Vaporizer Pressure Relief Piping With Rupture Disc

115-3005 - Expansion Chamber Assembly

115-3006 Vaporizer Components

115.3020 - Vaporizer Control Circuit Wiring Diagram, 120 Vac

115.3021 - Vaporizer Control Circuit Wiring Diagram, 240 Vac

115.3024 - Vaporizer Heater Circuit, 208, 240 & 575 Vac, 3 phase

115.3025 - Vaporizer Heater Circuit, 380 & 480 Vac, 3 phase

115.6010 - Gas Pressure Reducing Valve, ADVANCE Series 861 Instruction Manual

115.6020 - Gas Pressure Relief Valve and Rupture Disc Instruction Manual

1.2

Component Description

Series VAX4600 Vaporizer utilizes an electrically heated water bath to add the necessary heat to the liquid
chemical for vaporization. The unit consists of a hot water tank, a chemical vaporizing chamber, a NEMA 4X
heater control circuit, a NEMA 4X water level control circuit, chemical and hot water monitoring instruments,
cathodic protection circuit, and ABS structural foam enclosure.

NOTE: The standard vaporizer is not recommended for outside, unprotected installations.

1.2.1

Water Tank

The water tank is constructed of corrosion-resistant welded stainless steel. It houses six electric
water heaters and all water condition sensing and control devices (e.g. water level, water
temperature) in a standard NEMA 4X design.

1.2.2

Chemical Vaporizing Chamber

The chamber is constructed of 6" Schedule 80 steel pipe. Its all-welded construction conforms to
ASME codes for unfired pressure vessels. Externally mounted fins are utilized to aid in the efficient
transfer of heat from the water bath to the liquid chemical. Internally mounted baffles aid in
superheating of the chemical vapors and dropping out entrained liquid droplets as they rise from the
liquid level to the vaporizer discharge. See Figure 1

The vaporizing chamber also houses the chemical monitoring sensors for temperature and pressure.

NOTE: 

Superheat is the increase in the gas temperature above the boiling point at a given pressure

(minimum 10°F [5.5°C] above boiling point), and is required to prevent the gas from reliquefying as it
flows in the system. See Figure 2 for boiling points. Heat tracing and/or insulation of gas pressure
piping is recommended to maintain superheat. Loss of superheat may cause reliquefaction and
subsequent damage to the gas feeder.