Based in Buxton, England, Selden Research develops and manufactures cleaning and hygiene chemicals for both the professional and retail sectors.
Products are made available both under the Selden brands and private labels, and as bespoke formulas for customers. It also makes bespoke formulas for clients in the cleaning industry. It is an independent company manufacturing a wide range of specialised cleaning and maintenance chemicals for the professional cleaning, industrial and automotive markets. In 1973 five years after its inception the company moved to its present six acre site. he original purpose built factory has undergone numerous extensions to its present 73 000 sq ft. A further 10 acre site (just across the road) with 80 000 sq ft was purchased in 1999, this has been partially redeveloped with 24 000 sq ft remaining and currently in use, housing its British Institue of Cleaning Science approved training centre.
The company has just taken delivery of two stand-alone automated blending plants designed by SPX Process Equipment (SPX PE). These are designed to optimise processing efficiency in the production of motor vehicle windscreen wash at the Buxton plant.
The purpose-designed systems bring together alcohol, water, colourings, perfumes and surfactants in preset quantities and flowrates to service Selden's bulk filling lines or production storage tanks as required (Fig.1).
According to Mike Scott, process systems product manager at SPX PE, the requirement was for two systems offering the capabilities to produce a variety of screen washes ranging from 15-85 per cent alcohol (IMS) diluted with water in total production volumes up to 9000l/h.
Metering pumps for paints
Each system comes with a Bran + Luebbe touch screen display PLC control panel for easy recipe selection, together with specification of the flowrate and batch size requirements. In designing and building the two systems, SPX PE has drawn on several of its technologies and product ranges. In order to transfer alcohol stored externally in a bulk storage area to the main processing rig, each system is fitted with a remote progressive cavity pump.
At the rig, water is pumped using a Johnson Pumps centrifugal (Combibloc) unit from a local break tank through a flowmeter.
Depending on the specific product, a concentrated pre-mix of surfactants, perfume and colouring dye is introduced to the rig from an IBC using a Bran + Luebbe ProCam metering pump and through an Endress + Hauser flowmeter with pulsation smoothing software.
"The alcohol and water is mixed in-line using a Bran + Luebbe static mixer," says Scott. "It passes through a mass flowmeter where we can measure the total flowrate and the density of the mix. From this we can derive total flows of both water and alcohol in order to see if we are meeting the required alcohol content."
The system uses PID control from the PLC to adjust automatically the relevant pump via speed control inverters.
The final operation is to create the finished product by bringing the premix and IMS/water solution together through a static mixer. This process is closely monitored and uses PID control again to ensure that the final product is always within specification.
Previously Selden created a batch of product manually, which was then transferred to a storage tank or directly to a machine. As the new SPX PE system runs in an 'on demand' mode or 'by batch', Selden reports that it frees up storage volume and manpower.
Metering pumps for paints
With its long experience in the paints and coatings industry, SPX PE offers a wide range of mechanically and hydraulically actuated Bran + Luebbe diaphragm pumps (Fig.2). Through innovation and the ability to use a wide range of materials, current diaphragm pump designs can accommodate a wide range of flows and other process variables such as pressure and temperature
Within the paints, coatings and finishing industries, for example, there are many applications that involve single and multiple streams where the liquids need to be metered accurately to ensure product consistency.
Hazardous to health
The individual components that comprise these applications often require careful handling as they can be both flammable and hazardous to health. They are also expensive commodities so need to be handled efficiently and economically to avoid waste.
The production of PVA emulsion is a perfect example of where multi-headed dosing pumps come into their own and it is an application where Bran + Luebbe pumps have a strong reputation.
In this application units using three multi-headed double diaphragm pumps operate at a high pressure to combine vinyl acetate and monomer.
Final product consistency is maintained through the use of electric stroke length adjustment, which allows for fine tuning of the components within this fully automated production process.
In the automotive industry there are many applications, including the blending of base coats and formulating of colours, where this type of pump has a high international operating base. In one specific UK plant, the Bran + Luebbe pumps are being used within the topping-up systems for base coats.
Handling pigment and resin, each pump head operates independently and delivers product at varying pressures and flows according to production requirements.
Elsewhere, single headed pumps are being used for handling passivator, accelerator, cleaner surfactant and phosphate on a pre-treatment line.
Pump speed/flowrate and process pressure vary at line on a car to car basis depending on the colour required.
In all cases, the proportion of each component is an essential requirement in order to ensure a uniform final product.
According to SPX PE, the main advantage of double diaphragm pump heads is their ability to provide leak-free operation and prevent the safety and environmental problems associated with the escape of dangerous chemicals into the atmosphere.
The solution employed by the Bran + Luebbe pump, in combination with a rupture detection device, has been shown to be highly effective.
Should one diaphragm rupture, the second will continue to function without any detriment to the pumping operation.
In such an event the rupture device will alert operating personnel and appropriate remedial action can either be implemented immediately or at a convenient time in the manufacturing process.
Improvements in speed and stroke control parameters allow greater pump flexibility as well as contributing to very high levels of accuracy and consistency, ensuring efficient use of the expensive raw materials.
Positive displacement pump technology has been shown to be one of the most effective methods for the inline proportioning and metering of liquids.
Such pumps display high levels of accuracy, repeatability, safety and economy particularly if they provide leak-free performance.
Meeting industry requirements
According to the company, developments have kept pace with industry requirements and the continuing introduction of new manufacturing processes and materials will ensure that these pumps will maintain their position as an integral part of the processes employed in paints, coatings and finishes processing.