_{(C) 2004-2009Primary  Flow  Signal, Inc. - all rights reserved.}

HEADQUARTERS

Primary Flow Signal, Inc.
800 Wellington Avenue
Cranston  RI  USA   02910 
(ph)877-737-3569
(ph)401-461-6366
(fx)401-461-4450
Dezi@primaryflowsignal.com


 

HVT-SM SEALED METERING SYSTEM

HVT-CI Halmi Cast Iron Venturi Meters
begin their journey to the customer.

The HVT-Halmi Venturi Flow Element design, developed and perfected by Dezsoe Halmi, founder of Primary Flow Signal, Inc., is a proprietary design offered exclusively by the company for high accuracy and high reliability flow measurement of pressurized line fluids including liquids, gasses, and steam.  

In its embodiment as the HVT-SM Sealed Metering System, this patented revolutionary design facilitates the flow measurement of high viscosity line fluids, solids bearing line fluids as well as harsh and/or contaminated line fluids.

This design is available in a variety of configurations, including cast iron pressure vessel, fabricated (welded) metal pressure vessel,  plastic insert style, welded insert style, and welded-in pressure vessel style.  Additionally, the HVT is offered as a cast in place (usually concrete and typically rectangular) configuration.  PFS, Inc. applications specialists can help you select from the wide range of standard product configurations that we have available, or our engineers can custom tailor a solution for your specific and unique application requirements.

GENERAL INFORMATION
The HVT-SM Sealed Metering System is a crucial  refinement of the fundamental HVT design. Conventional differential producer designs depend on piezometer taps for differential pressure sensing that consist of openings not usually larger than 3/4" and most routinely range in lesser fractional sizes.  An entire range of flowing media characterized by materials such as sewage, pulp and paper industry flowing media, and hydrocarbons, for example, resist proper consistent and reliable measurement by conventional means due either to rapid accretion of the solids in the line fluid creating impenetrable blockage between the piezometer taps and the differential pressure transmitter (manometer or other pressure sensing means), or by introducing gas bubbles or vacuum into impulse lines thereby causing deterioration, if not complete loss of accurate and reliable flow measurement.

As well, applications involving hazardous or contaminated substances, or high temperature line fluids will, inevitably, destroy the internals of the conventional differential pressure transmitter, similarly rendering the accurate and reliable flow measurement thereof impossible.

The HVT-SM Sealed Metering System relies on the thoroughly substantiated and time tested HVT-hydraulic shape for its flow meter body configuration, however, it incorporates a 3 inch remote seal for sensing the high pressure in the inlet, and a 3 inch remote seal for sensing the low pressure in the throat.  In addition, each assembly is equipped with proper valving, and calibration ring to permit in place calibration of the system, or withdrawal of the sensors for maintenance or replacement.

This design, therefore, eliminates any possibilities of clogging, adverse effects of pulling a vacuum in the throat, gas bubbles formation or deterioration due to harsh, hazardous or contaminated line fluids.

DESCRIPTION OF THE  HVT-SM Sealed Metering System

Features and Benefits of the HVT-SM Sealed Metering System
While competitors have attempted to duplicate our novel design (without violating our patent protection) it is important to note that our design works, while the competitors designs are far less accurate, and susceptible to failures of which there are many examples, unfortunately enough, for the unwary buyers.

Similarly, alternate technologies such as magnetic flow meters and/or ultrasonic meters are promoted with claims that are rarely supported by proper and conclusive technical and empirical substantiation.

• The HVT-SM Design is Proven and Substantiated - The basic accuracy of the HVT-Halmi Venturi meter is indisputable, based on the substantiation work and continuing research in the form of wet calibrations in various independent and certified laboratories each year.  The benefits of this design can, however, quickly be destroyed were one simply to substitute standard taps with sealed diaphragms and have at it.  Our intensive research and development contemplated issues including consideration of the effects of inadvertent partial sealed sensor withdrawal on accuracy and reliability, the effects of varying diameters, design and composition of the sealed diaphragms, and the effects of line size and beta on the application of the HVT-SM technology.  Acquiring a Sealed Metering System not only provides the hardware itself, but  more importantly, it provides the integration of the hardware into a tested and proven system, built within specific and critical tolerances, all synthesized to result in a product that performs exactly as promised, and is backed up by the warranty to prove it.
• The 3 inch Diaphragm - Our standard systems are equipped with 3" diameter sealed diaphragms, attached to capillaries permanently connected to the DP cells, factory sealed for assurance.  While imitators will occasionally attempt to propose systems using 1" diameter diaphragms as cost savings measures, our extensive experience and research reveals that the accuracy of smaller diameter seals, on the order of 1 inch, are significantly inferior, due to nothing more than the simple fact that the deflection range of the smaller diameter renders it less flexible and thus incapable of the range of movement necessary to accommodate the variations in flow rate range that necessarily accompany any application environment. Most reputable manufacturers of remote seal transmitters will readily confirm and admit that using a 1 inch diameter seal is technically unacceptable.
• The HVT-SM in-place Calibration - The HVT-SM Sealed Metering System is equipped with an integral calibration means to permit the operator to periodically calibrate the DP cell readings resulting from the sealed sensors against either a manometer or another DP cell, without removing the entire HVT - SM Sealed System meter.  This is a major advantage as compared, for instance, against a magnetic flow meter.  Mag-meters need initial calibration prior to installation in exactly duplicated installation conditions, in order to have a possibility of providing some sort of accuracy.  Since mag-meters are prone to drift, when the mag-meter needs to be calibrated again ( as they all do) the mag-meter must be removed from the line, replaced with a spool piece, and calibrated in a lab, somewhere.  The HVT-SM never needs to leave the line, and all service and/or maintenance can be accomplished without any interruption to the process operation.
• Low Head Loss-No Minimum Line Velocity - The standard HVT-SM has the same headloss characteristics as are obtained with standard HVT-Halmi Venturi Meter design since the geometry is identical with the exception of the tap arrangement.  Therefore, the sealed metering system provides a very low energy technology.  Certain other technologies, for instance, mag-meters, will tout "no headloss" in their claims.  One must, however, keep in mind that the mag-meter requires certain minimum velocities in order to achieve its performance envelope.  This often requires the mag-meter to be of a smaller diameter than the existing line size in order to achieve the needed line velocity.   Naturally, in so doing, the headloss resulting is substantially higher, and in some cases can exceed that of the HVT-SM.  
• Unaffected by Air Bubbles or Vacuum - with certain applications, it is not uncommon for the line fluid to permit gas bubbles to bleed out, or for gas pockets to develop during process cycling from low flow to maximum flow conditions.  In other instances, if a system is driven to a higher flow rate where the throat pressure becomes negative, conventional meter arrangements may fail to respond due to the vacuum condition. With the HVT-SM, neither gas bubbles nor vacuum conditions have adverse effects on the ability of the system to perform accurately and reliably.  This is due to the fact that the impulse line medium is physically sealed off from any direct contact with the line fluid, hence, normally detrimental conditions of the line fluid will not influence the measurement. 

Notwithstanding the many advantages of the HVT-SM Sealed Metering System, it is possible that application conditions will exceed the capabilities of this metering technology.  In such cases, we recommend that due consideration be given the PFS-Wedgetype^TM meter.

HVT-SM-RAS RETURN ACTIVATED SLUDGE
Find a brief description of the HVT-SM - RAS Halmi Sealed Metering System for Return Activated Sludge, along with features and  benefits of this design.

For more information on the HVT Halmi Venturi Meter see:

HVT-GENERAL INFORMATION
Find a brief description of the HVT-Halmi Venturi meter along with features and  benefits of this design.