All HVS Systems are designed to be used with an existing LPG vapor source, such as a vaporizer, or as the replacement for less efficient or less reliable LPG-vapor/air mixing systems. They come complete with steel skid, vapor inlet header, venturi arrangements, surge tank, electric/electronic controls, and all other equipment necessary for safe operation. The produced gas is directly compatible, and interchangeable, with NatGas.

All HVS systems monitor the gas pressure in the surge tank. Smaller systems up to two venturi arrangements use pressure switches and standard controls. Larger systems with three or more venturi arrangements use a pressure transmitter which is connected to a Siemens or Allen-Bradley PLC. The PLC “sequences” the venturi lines and controls all system safety functions. The PLC also communicates with a color LCD display with Touch Screen Operator Interface, indicating system pressures, and any trouble conditions that may occur. The PLC may also be used to “interlock” the HVS system with an external vaporizer.

Installations where the mixer system is separated from an open-flame vaporizer, and installations with electric vaporizers, require the option “Explosion Proof Control Components”, which includes explosion proof transmitters and solenoid valves. The control panel for these mixers must be installed in a non-hazardous location. A local start/stop station in an explosion-proof enclosure provides basic control over the mixer. The main control panel for these mixers, with PLC and operator interface, must be installed in a non-hazardous location.

All HVS Mixers are equipped with two solenoid valves per venturi train. The “dynamic” solenoid valve opens and closes each time a venturi train is activated to produce mixed gas. The “static” solenoid valves opens when the mixer is started and stays open until the mixer is stopped, or until a high-pressure alarm occurs. This feature provides an additional level of safety and prevents the unwanted discharge of mixed gas in case of a failure of the “dynamic” solenoid valve.

HVS mixers with electronic controls (PLC) allow the adjustment of the sendout pressure and the sequencing of the venturi lines (differential pressure between trains; ON‑OFF deadband) through simple inputs at the operator interface. These versions also offer a “Venturi Cycle Counter” for each venturi train. The counter increments each time a venturi train is activated. This information can be used to determine when the mechanical components of a venturi train should be closely inspected, overhauled, or replaced.

The required vapor supply pressure depends on the desired sendout pressure, on the type of available LPG (Propane/Butane content), and on other factors (i.e. altitude). Typical supply pressures for “Propane” and 5-8 psi sendout pressure are 50-70 psi. Systems with higher sendout pressure of 9-12 psi require considerably higher vapor supply pressure, which can be difficult to maintain in very cold climates. Mixed Gas Sendout Pressures of more than 12 psi require the High Pressure option, which includes an ASME “U”-stamped surge tank.

Please Note:
Venturi-based LP/Air mixers are generally considered “for intermittent use”. Due to the relatively limited useful life of their dynamically exercised mechanical components (regulators, check valves, solenoid valves, air intake valves, etc. are typically specified to withstand 200000 to 500000 cycles), they are not very well suited for baseload applications. Their main application is “Emergency Backup”.

Compact HVS:        
Models with one or two venturi trains (HVS-7, HVS-10, HVS-14, HVS-20) are also available in “Compact” configuration. These models are specifically designed for air freight shipment (small footprint, reduced height, removable relief valve stack, etc.). There is no price adder for these models.