Article: Operating Principle of Equilibar Back Pressure Regulators
To understand what makes Equilibar different and overcome it's competitors, follow this link to read our article Operating Principle of Equilibar Back Pressure Regulators
Our range of back pressure regulators are all manufactured by Equilibar. We distribute for a variety of applications which include vacuum, industrial, high temperature, sanitary, general use as well as for research and development.
To understand what makes Equilibar different and overcome it's competitors, follow this link to read our article Operating Principle of Equilibar Back Pressure Regulators
Applications for Equilibar Back Pressure Regulators are present throughout Research, Academia, Industry, Chemical and the Oil & Gas Industries to name just a few. Some applications could include:
Please find these examples explained in detail below:
The control of pressure in flow chemistry is important for a number of processes, for example phase control, residence time, reaction speed and equilibrium management. It is well known that the reaction temperature has a marked effect on reaction efficiency, however, at high enough temperatures a reagent might reach boiling point that then negatively impacts the reaction efficiency. By controlling the reaction pressure, adding a back pressure regulator to the outlet of the reactor, the boiling point is increased and efficiency is maintained.
Heated reactors are used within most catalyst research studies, often beginning with multiple parallel trials at the micro-scale and gradually increasing in reactor scale up to the semi-works facility whereby practical catalyst performance can be studied up at the kilogram scale. Depending on the catalyst market, pressures vary from near 1 bar, for environmental catalysis, up to 300 bar for many petrochemical conversions. Importantly, it is the reactor pressure control that is key to catalyst research. The Equilibar Research Series is designed and demonstrated to excel within the demanding requirements of catalysis research.
Within many research protocols it is essential to have liquid level control within a steady state stream to ensure repeatable and consistent mass balance calculations whilst keeping the pressure and other process variables stable. With so many variables within these systems a typical “on/off” level control valve is simply not up to the job. An Equilibar® back pressure valve (BPV) however can be used as a level control valve in this case to control steady state liquid flow through a range of flow coefficients exceeding 1000:1. Speed, repeatability and responsiveness is achieved via a feed-back loop with an electronic pressure regulator acting as the pilot valve to the dome. An analog level sensor provides input to the PID.
Traditional dental suction systems experience significant changes to the level of vacuum available depending upon the number suction tools being used at any one time. This is because they are generally unregulated, and the more users operating with the system reduces the amount of vacuum being available. Regenerative blowers typically have flow curves that drop from the 10 inHg range at low flow to the 5 inHg range at high flow. Other systems such as dry vane pumps and liquid ring pumps can pull a stronger vacuum although because of this they need to be provided with a spring-loaded vacuum breaker to limit the maximum suction available. All of these systems experience significant changes in vacuum based on the number of simultaneous tools active on the header. The Equilibar vacuum regulator is ideal for use with dry-vane vacuum pumps because it produces a nearly flat pressure curve throughout the operating range of the pump. Such an approach allows the user to select the ideal vacuum level without having to compromise on the engineering due to the extremes of vacuum level at low versus high usage.
Altitude test chambers are used by many different industries to mimic changes in altitude to simulate the conditions of varying atmospheric pressure, temperature, and humidity. As an example, within the automotive sector; before departing on actual Winter Testing, anticipated performance and emissions must be mapped for various altitudes. Similarly, high altitude simulation chambers are also required to test pilot masks and other cockpit equipment and recently athletes have begun training in altitude chambers that simulate the low-oxygen conditions found in mountainous regions to build stronger blood oxygen capacity. Equilibar has recently demonstrated a high precision altitude simulation regulator which dramatically increases the accuracy and stability of large test chambers. The dome-loaded vacuum regulator uses a precision set-point signal from a high speed electronic pressure regulator. The direct-sealing diaphragm regulator translates the small pressure signal from the electronic pressure regulator 1:1 to the much larger air flow coming from the test chamber.
In many tubing and extrusion applications, such as hydraulic hose, medical tubing and door seal profiles, it is essential that the both the outer diameter and the wall thickness be maintained within prescribed tolerances. This is especially difficult if the extruded material has little hot strength i.e. it tends to collapse in on itself or if it is prone to sticking to itself. To increase control, air can be introduced into centre space (lumen) of the extruded tubing, however, the pressure must be closely and swiftly controlled to avoid either over- or under-inflation. Similarly, it must be swiftly self- adjusting to downstream perturbations such as compression caused by rollers, cut-off machines, punches or saws and variations in windup processes. The installation of an Equilibar low pressure control system to control the pressure of the air inside the extrudate gives precise control of the dimensions and allows more repeatable process start-ups.
Reservoir Engineers have a special requirement for BPR's within their physical analysis of core samples. In conventional core analysis, samples are analyzed to determine the recoverable hydrocarbon content that is evolved at different temperatures and at different points within the time cycle whilst maintaining a pressure consistent with the reservoir’s original overburden pressure. In core flooding experiments, permeability of the rock to gas, oil, and brine is measured. Back pressure regulators are a key component of many core analysis applications. While some core analysis experiments use inert gas flow through the sample to transport the hydrocarbons, many other core analysis applications require that the sample reactor maintain a constant pressure under no-flow conditions. For example, a rock sample may evolve no gases or hydrocarbons during the early part of a temperature ramp, but later evolve significant flows of condensable hydrocarbon gases as the temperature ramps up. A back pressure valve is often located downstream of the core sample reactor to maintain the “overburden” pressure during core flooding. The ideal BPR can hold the reactor pressure at a very stable pressure even as the flow rates vary from true zero flow up to high flow rates (typically tens or hundreds of ml/min).
The Precision BPR available from PCT is the perfect fit for many fuel cell applications. This is because fuel cell testing systems specifically benefit from the high sensitivity of the BPR in the low to mid pressure ranges that is lacking in most competitive products. Indeed, the “GR” coded trim was specifically designed in response to the demanding flow rate requirements of the fuel cell testing industry as these GR trim regulators provide stable stack pressures throughout the ultra-wide flow rate ranges that are required for rigorous test protocols.
Bio Technology, Bio Pharmaceutical and other hygienic/sterile processes have unique requirements for control valves because of Clean-In-Place (CIP) flow requirements. Back pressure control valves that can precisely control at low and medium dosing flow rates whilst also maintaining very high CIP flow rates have been a rarity until now. Standard CIP requirements are to achieve 5 ft/sec of fluid velocity during the cleaning process to assure good flushing and rinsing. If 2” (DN50) tubing is used, for example, then a CIP cleaning and rinsing flow rate of nearly 45 GPM is required. Sterile/hygienic processes are typically designed such that several serial components are cleaned at a time e.g. a pump, filter, transfer line and several valves might all be part of a cleaning loop. The Equilibar Sanitary FD series functions in a unique way compared to other sanitary valves. Instead of using a globe-style valve seat with limited flow range, it uses a direct sealing diaphragm and 1:1 dome air loading to modulate the pressure and flow. The interaction of the flexible diaphragm and the dozens of parallel orifices allows for a very high Cv turn-down ratio. This exceptionally broad flow range allows the process engineer to specify a single valve capable of precise control during dosing and blending, while also opening up during the Clean-In-Place process to facilitate robust process flushing.
Equilibar BPR's can be used to reduce pulsations in circulating liquid systems, such as used with positive displacement pumps. A common use is to control pump pressure in a circulating system where a portion of the flow can be recirculated to the supply reservoir. The outlet pressure of any type of pump can easily be controlled in this manner. Where the pump is a positive displacement type, the higher pressure spikes will be preferentially reduced by the fast acting multi-orifice design of the Equilibar BPR especially as they are sensitive to pressure changes as small as 0.01% of overall set-point. The Equilibar gas-loaded diaphragm also provides a very significant pulsation dampening effect just upstream of the valve orifices.
Equilibar offer many advantages for liquid pressure control across a great many industrial environments. At the very heart of their success is the fact that they are actually very simple devices with just one flexible moving part. The simple flow path makes them ideal for sanitary and hygienic applications. Equally, the simple design also enables the inclusion of a great many wetted materials, especially exotics, thereby making them ideal for highly corrosive fluids.
Perishable or sensitive goods such as fresh meats, fruit, vegetables and cut flowers are packaged or transported within Modified Atmosphere Packaging (MAP) whereby air is rapidly removed and replaced by an inert gas. To do this economically, the gas exchange processes must occur extremely quickly, challenging the performance of traditional gas handling components and systems. By providing stable vacuum pressures under rapidly varying flow rates, the Equilibar regulator dramatically reduces the atmospheric variability from package to package, thereby improving the quality of the product and the productivity of the process.
The modern method of distributing products via packaging involves the use of high speed filling machines that quickly fill vials, bottles or containers with pharmaceutical or consumer product. It is a relatively complex process with many considerations such as constant nozzle pressure and careful nozzle valve timing being especially critical. Other important factors are how best to control the flow rate and pressure drop throughout the system in order to optimize the competing demands of throughput, product consistency (or quality) and machine uptime. Other challenges arise when viscous fluids are involved, not only because of the pressures and low flowrates involved, but also because such systems often need to be designed to include much higher flow rates of flushing and/or Clean-In-Place chemicals. Installing a high-speed back pressure regulator near the exit of the nozzle manifold can address these challenges. The Equilibar Sanitary FD is especially well suited for this purpose as it responds virtually instantaneously to pressure changes with frictionless operation due to its only moving part simply being a flexible diaphragm. In addition, the FD is a dome-loaded pressure regulator with pilot operation, resulting in superior accuracy and precision.
In fuel system component testing, it is desirable to perform development and quality assurance tests at or close to actual operating conditions. This means varying the back pressure and the rpm of the unit(s) during the testing cycle. Varying speed is a well known process, but varying back pressure may get complicated or costly. Equilibar Back pressure regulators can simplify the design of the test rig and provide reliable service under high cycle service. Benefits: The pressures can be cycled rapidly to create high cycle style life tests in a relative short period of time.
Traditional refrigeration systems circulate a liquid/vapour mixture to the evaporator coils where conversion back to homogenous vapour takes place. While it is possible to control the heat transfer rate into the evaporator, it isn’t feasible for a traditional system to control the temperature of the evaporator coil directly. Equilibar’s method makes it possible to make extremely fast and precise temperature changes to the evaporator surfaces directly. It is even possible to maintain the coil temperature exactly at the saturation temperature corresponding to the controlled fluid pressure. During modulating heat transfer conditions, two-phase refrigerant (saturated vapor and liquid) will pass into the BPR and expand into vapor inside the valve. When maximum cooling is needed, the Equilibar BPR opens, dropping the evaporator pressure and allowing maximum evaporation in the coil. As the pressure setting is reduced, an immediate boost of cooling is obtained from the latent heat of the liquid rapidly vaporizing on the tube surfaces. The process control benefits from both the dynamic evaporation boost as well as the steady state heat transfer control. This is possible because the Equilibar BPR works in a completely unique way. Its multiple orifice design is capable of maintaining pressure control even with uneven slugs of vapor and liquid entering the valve.
Many laboratory catalysis reactors utilize a high pressure liquid separator downstream of the reactor. In addition to this expensive separator, such processes typically require a liquid level control loop in parallel to the gas phase BPR. As an alternative to this traditional complex and expensive approach is the use of a single Equilibar back pressure regulator for both phases at the same time. It is therefore possible to eliminate the high pressure separator and the level control system downstream of the reactor.
Tangential flow filtration (TFF) is widely used across the Biotechnology and Biopharmaceutical industries as it is a highly efficient method for purifying biomolecules. During the filtration process, the differential pressure across the TFF membrane must be maintained within a narrow range to provide the best results. Equilibar® back pressure regulators with their multi-orifice design delivers superior precision and can accurately control the differential pressure across a wide range of flow rates. 316L multi-use pressure control valves and polymer single use designs are used in both the retentate and permeate lines of the TFF process.
Chromatography columns are used in the BioPharma industry to concentrate and filter active ingredients or drug components. These columns are typically packed with activated particles with high surface area and can either retain desired components (such as antibodies in affinity chromatography) or filter out undesired compounds (such as protein A in ion chromatography). Typically, more than one type of these columns are used in series to provide the concentration and purity required. These columns not only dilute or concentrate drug solutions but also process streams of critical fluids such as electrolytes, buffer solutions and elution acids. Typically these fluids are controlled with sanitary control valves or gear pumps and the flow rate often measured by expensive Coriolis flow meters for high accuracy. Equilibar back pressure regulators are useful for providing necessary back pressure for dosing pumps to prevent pump slip problems at very low dosing flow rates and can be used as the primary flow control valve to avoid bulky globe valves and extend the flow control turndown range beyond 100:1 (from 20:1).
Some industries still use thermal or heat transfer flow measurement techniques for their mass flow readings as opposed to the clear benefits of Alicat mass flow instruments as described elsewhere within this website. Thermal instruments depend on constant gas density for accurate calibration and Equilibar precision back pressure regulators are perfect for highly stable pressure control across a very wide range of flow rates. Commonly a primary calibration device is used to define a known mass flow rate to Device Under Test (DUT). The Equilibar BPR keeps a constant back pressure and therefore gas density on both instruments. Typical spring-type back pressure regulators operate through a relatively narrow flow rate range, such as 10:1. Below a certain flow threshold, they cannot hold back target pressure and exhibit “under-pressure”. As the flow rate increases to the upper end of their range, the spring compresses and the inlet pressure increases (“Over pressure”). This under-pressure and over-pressure can cause considerable delays within the calibration process as the knob must be constantly adjusted to keep the gas at constant density. It has unmatched sensitivity down to the ultra low pressure range and can increase the accuracy of real gas MFC calibration.
With expanding research into such areas as carbon capture and sequestration, solvent replacement within herbal active ingredient extraction and the alternative energy sector, there is an increased demand for pressure regulators to perform in applications controlling supercritical carbon dioxide (SCO2). Equilibar® precision back pressure regulators are being used successfully in research reactor applications using supercritical fluids. The H6P and B6R regulators are rated up to 6000 psig, giving scientists and engineers a new tool for precision pressure control whilst the BR Series of blockage resistant BPR's were specifically designed for SCO2 applications.
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