New Honsberg high-pressure flow switch now available from PVL

New diaphragm materials for steam and food applications

Beck has equipped its Model 901 Pressure Switch with a newly developed diaphragm material. The basis for the saturated steam-resistant version is a special, newly developed FKM elastomer material.

This new material allows direct contact possible with aggressive saturated steam for example. As a result, the series 901 pressure switches are advancing into new temperature zones up to 140°C and, depending on the model, can be adjusted to provide switch-points from 100 mbar up to 12 bar without material fatigue.

Conventional elastomers can quickly lose their elasticity when used with saturated steam resulting in a detrimental shift of the switch-point. In extreme cases, they become brittle or cracked and so represent a potential danger as a result of failure.

Also, a new diaphragm suitable for food processing is available from Beck. EPDM meets the requirements of the FDA Standard (21-CFR 177.2600

PVL has added a high temperature version to its RFS range of versatile and highly cost-effective liquid level switches. Suitable for use in a wide range of liquids, the RFS-12H provides heat resistance up to 180°C, with a rugged, simple design that brings maximum reliability to high, low or intermediate liquid level detection.

This miniature, side entry level switch provides user-selectable NO or NC contacts, and can be rotated by 180°, allowing a single device to provide rising-on, rising-off, falling-on or falling-off functionality. Simple in design, the principle of operation is a magnetic reed switch, where the magnet-equipped float moves up and down with the liquid to actuate the switch within the unit stem.

The RFS-12H is available in two mounting options for added convenience, allowing the device to be secured from either the inside or the outside of a tank. The internal model has a 1/8in BSP parallel thread with a running back nut, while the external model has a 1/2in BSP taper thread. Both have been designed to offer maximum resistance to shock and vibration.

Electrical connection is made via flying leads,. maximum switching voltage is 300V AC/DC and maximum switching current is 0.5A AC/DC, with the contacts rated at 50W. The high temperature resistance, combined with a variety of construction materials and a float specific gravity of just 0.7, make the RFS-12H suitable for use with a wide range of liquids in a variety of applications. As well as standard tank level duties, the RFS-12H is suitable for use in chemical processing systems, in automatic safety interlocks, in pump motor control systems, and other challenging applications.

This simplicity of design is the key to both the high levels of reliability and the low price, with the high temperature RFS-12H available at just £35.00

PVL now offers an extensive range of flow and level switches with ATEX certification, extending the scope for uses of these fluid control products in hazardous, potentially explosive areas. The range includes piston valve designs, piston inline designs and paddle designs for flow control, plus a float switch for level control.

ATEX became a harmonised standard across Europe in July 2003, stipulating stringent requirements for the electrical components of instruments used in hazardous areas, where even the slightest spark could cause a devastating explosion.

The new range of flow and level switches features switch heads certified to ATEX Directive 94/9/EC, married to a wide variety of mechanical flow control bodies. The products provide intrinsic safety level protection by limiting energy and temperature and minimising the risk of arcing. As such the products may be used in Safety zones 0, 1 and 2, in application areas such as offshore platforms, petrochemical plants, mines, flour mills and other areas where a potentially explosive atmosphere may be present.

New from PVL is an adjustable pressure switch that will simplify the lives of engineers who need to tweak hydraulic, pneumatic or lubrication systems during set up, or who need to monitor system pressures on the fly. The innovative PSK pressure switch provides simple adjustment of system pressures, with two models covering the key ranges of 10-100bar and 100-360bar.

With its large adjusting knob, easy-to-read graduated pressure scale and fixed hysteresis, the PSK provides simple yet reliable adjustment of system pressure, and has been particularly designed to help engineers monitor and set minimum or maximum pressure in fluid circuits. Once the correct pressure has been established, the device can be locked off via a set-point fastening screw.

Whilst the PSK is not intended to provide absolute accuracy, it will prove an immensely useful tool for adjustment in the field, and the accuracy available belies the simplicity of the adjustment mechanism, comments PVL's Steve Moorey. It would be invaluable for hydraulics engineers who need to set pressure relief valve switches, but who don't actually know the required pressures until they get out in the field.

Rugged and robust, the PSK adjustable pressure switch is constructed from anodised aluminium, and features an aluminium adjusting knob, with the whole construction sealed to IP65. Mounting options include CETOP manifold or 1/4in BSP pipe fitting, affording high levels of mounting flexibility.

Based on proven pressure switch technology, the highly reliable device offers a mechanical life in excess of one million operations.

PVL has introduced a new range of pre-set pressure switches featuring an integrated M12 connector and offering a sealed design protected to IP67. Available for pressures from 0.2 to 300 bar, the new switches provide inherently reliable operation in highly demanding applications where even IP65 protection is not enough to ensure long term reliability of the switch or, in extreme situations, the assured operation of the connected circuitry.

The new MS/PS pressure switches with integrated M12 plug extend one of world’s largest ranges of fluid control products, and have been developed in response to increasing market demand for a rugged, compact, pre-set item with IP67 protection. The design integrates a 4-pin M12 connector into a newly developed protection cap to provide a product which guarantees high integrity whilst making installation quick and easy.

The IP67 MS/PS pressure switches will be of particular interest in mobile plant applications that face extreme environmental conditions beyond the sealing capabilities of even IP65 protection. The new switches will also provide a more reliable solution in damp or dusty industrial situations, or in the likes of machine tool applications where cutting oils are an ever-present problem and where IP65 protection is simply not enough,

Further, the new switches should also provide increased assurance of operation in applications where the pressure switch is connected to solid state control equipment, as PVL’s Steve Moorey explains: “The increased usage of solid state control equipment can make life a bit difficult for the pressure switch. The high currents associated with electromechanical switchgear help to keep the contacts of the pressure switch clean, but the currents through solid state devices are too low to have any effect. Gold-plated contacts in the pressure switch obviously help, but even so it can only take a few molecules of dirt seeping in through the seal to build up on the contacts before operation is compromised. The IP67 design effectively eliminates the problem.”

The IP67 MS/PS range is available in a huge range of options, covering adjustment ranges from 0.2 to 300bar, different diaphragm and piston seal materials, choice of body materials, a wide choice of thread connections, pre-set switching on rising or falling pressures, and high pressure or degreased execution. The result is a highly flexible and versatile range of products that will meet the needs of the widest possible range of applications.

MS/PS pressure switches provide a single-pole, double-throw (SPDT) contact configuration, rated at 250V AC, 3A. They also provide a specific pin for ground connection, to assure the highest levels of safety whatever the application.

New from PVL is a brochure detailing the Honsberg range of metering and control products for the control of gases or liquids at low flow rates. Standard metering and control products are generally unsuitable for use at low flow rates special purpose products are needed to ensure accurate control and good repeatability.

Honsberg has developed a series of products targeted at just such niche applications. The wide range of robust instruments includes piston, sphere and gearwheel switches, indicators and transmitters, all optimised to ensure reliable operation at low flow rates, even in high pressure or high temperature applications.

As well as highlighting the Honsberg product range for these applications, the handy brochure provides the engineer with invaluable general information on control of low flow rates, focusing on design considerations such as pressure loss, temperature, contamination, and installation position.

The brochure is written as the first in a series of guides which will build into an essential reference on niche flow control applications. Subsequent guides in the series will focus on areas such as flow control of dark and contaminated liquids, flow control in machine tools, flow control with ATEX approval, and viscosity compensated flow control.

PVL is an UK distributor of the Honsberg range of flow, level, temperature and pressure instrumentation, and for the company's range of filtration products.

PVL has brought limit switch design into the 21st Century with the launch of a compact, rugged and easy to mount range of limit switches with anodized aluminium bodies. Combining low operating force with a range of connection strategies (including push-on terminals or standard DIN plug) and IP65 construction, the Models FC1P and FC2P limit switches provide robust and reliable ON/OFF functionality in a huge spread of motion control, machinery safety, automotive and other industrial applications.

The new limit switches share the same bodies as PVL's range of high performance pressure and temperature switches, delivering a small, neat and fully industrialised solution whilst at the same time enabling the company to pass on the cost benefits afforded by volume manufacture.

Key features of the limit switches include their connection options and ease of mounting. Connection choices include push-on spade terminals (with an optional cover to maintain IP65 sealing) or standard DIN plug. The DIN plug version allows functions such as ON/OFF delay to be implemented as required, and the DIN plug is rotatable so that mounting the switch in a particular orientation is less of an issue. Installation of the limit switch into an application is achieved via its standard M12 threaded barrell.

The limit switches require a force of 200 grams to operate, and guarantee switching with a travel of just 0.8mm. Giving designers added flexibility when designing the limit switches into applications, the products offer a maximum travel of 3mm

The limit switches offer changeover contacts as standard, rated at 6A, 250V AC. Lifetime is specified at 1,000,000 electrical operations and a minimum of 100,000 mechanical operations at maximum rated voltage and current.

PVL has expanded its range of Omni transducers to include five new level and flow measurement options, in addition to the existing pressure, temperature and flow transducers. All are available in either flat face, 45° tilted face or positionable gooseneck versions, are sealed to IP67, and feature the patented Omni-ring contact-less setting technology which eliminates the need for the usual tiny front-fascia buttons that are often difficult to use and which compromise environmental sealing.

Two new level sensing transducers have been added to the range - a continuous level transducer which is custom-made to the appropriate length, and an ultrasonic level transducer. New flowmeter options include a gear type, a paddle type and a turbine type. And further Omni products are in development, including an infra-red temperature transducer.

Installation flexibility is a key feature of these products. The whole body of the display unit rotates through 180° to present the M12 connector at the optimum angle and the display head for easy viewing. For ultimate flexibility, the gooseneck option provides almost limitless freedom of positioning for the display head and allows higher operating temperatures to be achieved.

All models in the Omni sensor range are constructed in a modular way with regard to both hardware and software, making the products both highly flexible and cost-competitive. A 16-bit microcontroller with 14-bit A/D converter and 12-bit D/A converter delivers fast processing speeds and high accuracy measurement. The signal is displayed in engineering units using a back-lit LCD graphical display which is easy to read even from a distance. The device provides a standard 4-20mA output, and two switching points can be programmed over the complete range, with either PNP or NPN outputs.

Thoroughly engineered as robust industrial products, the transducers feature 316 grade stainless steel for most wetted parts, and display windows made from Swiss watch grade, toughened, scratch-resistant glass. The transducers are set-up using the contact-less Omni-ring which eliminates the need for any physical buttons or switches on the device and makes it easy to program even when wearing the thickest of gloves. The Omni-ring uses inductive technology to enable switch points, hysteresis, engineering units, output type and other parameters to be set, with the facility to protect settings with a security code. Parameters are set and adjusted by nudging the Omni-ring to the left and right. Once programming is completed, the Omni-ring can then either be reversed to prevent accidental re-sets, or removed completely. Setting of parameters can be performed with the process on- or off-line.

PVL are the UK distributors of the Balem range of flow (float) valves, which range in sizes from 1/2" to a massive 12"

The smallest model in the range is a direct acting valve with a stainless steel float on an actuating arm. The shut-off ball valve sits in a PTFE bearing which is contained in a brass or stainless steel housing. Thread sizes range from 1/2" to 2" BSP with pressure ratings up to 20 bar with the 303 grade stainless steel housing and 10 bar for the brass model. Temperatures can be as high as 110degC and a back-siphon prevention tube is available as an option.

The middle range Combi Model has a shorter actuating arm and operates on the pressure differential principle. This gives high flow rates and provides automatic level control for tanks with an integral adjustable flow feature. Sizes range from 1"BSP to 3" BSP with bodies available in cast bronze or stainless steel.

The Pistek model is specifically designed for even larger flow rates and can be specified with either an in-line or 90 degree cast iron housing. Because of the larger pipe diameters, the Pistek comes with flanged connections from 2½" up to 10" diameter.

The largest model is the Bescon which can be supplied to suit pipe sizes up to a massive 12" and it's stainless steel body is also available for de-ionised water applications as a special option. Like the Pistek, the Bescon can be supplied with a 90 degree (vertical) or in-line body and can work up to 15 bar and 80 degC.

A special feature of the Bescon range is an electrical over-ride. This means that the float valve can be operated electrically with a manual shut-off safety feature, or be operated manually with an electrical over-ride..

PVL Ltd has increased their range of pressure switches by adding two Intrinsically Safe models. Designated the PSM Exia and PSP Exia, these switches conform to EEx ia IIC T6 and are therefore approved for use in Zones 0, 1 & 2 if used with a suitable zener or galvanic barrier.

Four diaphragm actuated models are user adjustable from 0.2 to 100 bar, while two piston models are adjustable from 30 to 300 bar, with over pressure ratings of 300 and 600 bar respectively. Standard switches are supplied with a Nitrile diaphragm or piston seal, Silicon or EPDM being further options. Stainless steel bodies in 303 or 316 grade are also available to special order if the standard zinc plated steel body is not suitable for the intended application.

The switches have change-over (SPDT) contacts, a standard Din plug and a 1/4" BSP thread, although both Metric and NPT thread forms are also available. Degreasing for oxygen applications and free factory adjustment is offered to customers.

These new switches are good news for engineers who recognise that Intrinsic Safety (IS) is possibly the most dependable technique, and the only system permitted in Zone 0 applications. With prices starting at only £43.20 these are surely the most versatile and lowest cost IS pressure switches available in the UK.

PVL can also supply suitable barriers and other Intrinsically Safe devices for level and flow applications.

PVL introduce possibly the worlds smallest, all stainless steel level switch the RFS-13

Added to their range of pressure, vacuum, level, temperature and flow switches, this tiny side-entry level switch, has an insertion length of only 2” (50mm)

Like its family member the RFS-12P-2, the RFS-13 operates on the magnet & reed switch principle. Its 304 grade stainless steel construction makes it suitable for use in the processing, vending and hydraulics industries.

Designed for applications where space is limited, this level switch has a 1/8" BSP parallel thread with a running back nut to allow the switch to be fitted from inside the tank. Model RFS-13-2-A comes with an adapter allowing the switch to be mounted externally.

Capable of switching 24volts AC/DC, complete with 500mm of potted flying leads and withstanding operating temperatures of –40°C to +120°C this truly amazing miniature level switch will be of interest to engineers where space is at a premium.

The single order price for an RFS-13 is also small at only £30.00 each – with discounts available for volume orders.

PVL (Pressure-Vacuum-Level Ltd) have introduced a miniature , stainless steel, side entry level switch into the UK. Developed by Riko of Japan Model RFS-12 is claimed to be the smallest level switch of its kind available in the World, and operates on the magnet & reed switch principle. Its stainless steel construction makes it suitable not only for use in the processing and vending industries but also for hydraulics as the float SG is 0.7

Two different mounting methods are available. The internal model has a 1/8" BSP parallel thread with a running back nut to allow the switch to be fitted from inside the tank. The external model has a 1/2" BSPT taper thread which is ideal for applications where a threaded boss on the outer tank wall is preferred.

Both switches are suitable for use up to 240 volts AC and can be rotated through 180° to give either a normally open or normally closed contact. For increased versatility, the RFS-12 can be supplied with a mini DIN plug instead of the standard 500mm flying leads.

The single order price for both models is in the order of £30.00 each - discounts are available for volume orders.

It is common knowledge that using oxygen at its maximum pressure (that is to say 200bar) can be a real danger. At such pressures it is vital that switches be degreased for use with oxygen.

Along with degreasing, another important consideration for switches being used with Medical Oxygen, is the choice of diaphragm. Diaphragms should have a high structural stability because oxygen can combine with the diaphragm material leading to oxidisation of the switch parts hence reducing their durability. 

It is also necessary that the diaphragm has a very low permeability, as high permeability could cause the contact chamber to pressurise, resulting in irreparable damage to the switch casing, and rendering the switch inoperable. It is also strongly recommended that switches for use with medical oxygen use a valve plug, firstly to signal any leakage from the diaphragm, and secondly to provide an outlet for any over pressure build up.

PVL's (Pressure-Vacuum-Level Ltd) in colaboration with Elettrotec, are currently testing a revolutionary new kind of switch membrane of the FKM family. The main advantage of this new material being that it is suitable for use both with low temperature, and high pressures. 

FKM has the same characteristic resistance of the currently used Viton®, but in contrast has a very low permeability. FKM also allows low operating temperatures of -30°C, a figure well below that of the currently used Viton®. 

Elettrotec is hoping to have completed testing by the end of this year, and PVL is set to offer this option to its customers early in 2000.

PVL (Pressure-Vacuum-Level Ltd) have introduced a new piston actuated flow switch known as the Honsberg Model MR. This new switch is designed for use with a wide range of liquids and gases but has particular application in the field of hydraulics.

With a body available in either brass or stainless steel, pressures up to 200 bar and operating temperatures up to 120 degrees C can be readily achieved, with switch-point adjustments ranging from 0.4 to 80 litres/min. Special options can achieve higher flow rates, pressures up to 500 bar and flow rates from 0.02 to 600 litres/min

The Model MR can be mounted either vertically or horizontally and uses a magnetically coupled piston to actuate a change-over contact reed switch, it can also be supplied with an optional visual display if required. Viscosity compensated versions for thick liquids are available and for gases a 'damper' is fitted to reduce the possibility of piston fluctuations.

Being of all metal construction, the Model MR is considered superior to plastic flow switches making it ideal for many industrial control applications including cooling systems in tooling machines, gear lubrication circuits and most hydraulic applications. Standard fittings range from 1/4" to 1" BSP with special versions available up to 3" BSP.

These air and liquids flow switches can operate at relatively high temperatures up to 110⁰C and high pressures up to 25 bar, monitoring flow by means of a 'paddle' connected to a reed or microswitch.

They are available with tees from 3/8" to 2" BSP or with optional weld-in sockets for pipes up to 80mm bore. Flow status is confirmed by means of a Din plug with optional LED's and the set-point remains highly stable and highly accurate in use. The switch is magnetically operated with all electrical components isolated from the fluid and there are no seals to cause leakage problems.

A unique feature of the UR3 and UM3 switches is the IP65 protected, modular switch head which is identical for reed or microswitch versions. It is removable, yet removal doesn't disturb any electrical connections or flow set-point. It also has a concealed yet easily accessible adjustment screw.

These Honsberg flow switches can be mounted in any position, horizontally or vertically and are insensitive to dirt in normal operation. Available in brass or stainless steel as standard or optional PVC or copper these excellent switches are extremely competitively priced and are manufactured using state-of-the-art technology and modern precision manufacturing techniques.

A new, low cost flow meter operating on the magnetic-inductive principle, has just been launched into the UK by Crowborough, East Sussex based PVL (Pressure, Vacuum, Level Ltd.) Known as the FIS Flow Meter, it forms part of the Honsberg Smart series of instruments.

The FIS has been especially developed for pipe sizes ranging from 2" - 16" (DN 50 to 400mm) and can accurately measure flow of all conductive liquids, pastes and suspensions. The FIS is supplied with a stainless steel weld-in socket which is marked with pipe diameter graduations. Alternatively, the FIS can be fitted without welding by utilising an optional saddle clamp.

The FIS is supplied already pre-calibrated at the factory but also has a built-in self calibrating feature if required. The flow measurement range extends from 1 to 8 metres/second in 1 m/s increments and should the FIS metering assembly need to be removed from the pipework, then this can be readily achieved without loss of fluid or expensive downtime.

The FIS, which has no moving parts, is accurate to 2% of measured value if calibrated in situ and can withstand media temperatures from -25⁰C to +150⁰C. Wetted parts are 316 grade stainless steel and ceramic.

Apart from a standard 0(4) - 20 mA or frequency output, the Smart electronics also provide two programmable switch-points, hysteresis adjustment, an LCD display and trend indication. Further programming can be achieved by the use of an optional bi-directional infrared interface which can be used to up, or down-load data via a hand held computer terminal. An optional DIN rail or panel mounted display is also available with all the Smart features as above but also offers a choice of 24Vdc or 110/220Vac supply.

The FIS flow meter will eliminate the requirement for large flow meters typically required for large diameter pipework and PVL believe that its simplicity coupled with huge cost savings will be of immense interest to cost-conscience, discerning engineers. Uniquely, only one size is required for all pipe sizes and therefore the cost is the same irrespective of pipe size.

The optional (Psion) hand held terminal offers many extra functions and can be used to programme an extra twenty limit values, perform data logging functions as well as communicate with a standard PC.

The FIS flow meter forms part of a family of Smart sensors for flow, distance, level, pressure, differential pressure and temperature.