75 Years SIGRIST: Part IV: TurBiScat – a star is born

Since 1946, the name SIGRIST-PHOTOMETER AG has been firmly associated with turbidity measurement in beer filtration. We have also been committed to highest quality and precision, durability and reliability for more than 75 years. This is reflected in the continuous optimisation of existing products and the development of new ones. In 2009, for example, one further innovation was added to the SIGRIST portfolio – the TurBiScat. With its combination of precise dual-angle scattered light measurement, optional colour measurement and virtually maintenance-free operation, our in-line process turbidimeter is ideally designed to meet today's requirements of our international customers.

Highest quality, precision and measuring accuracy

The secret of our intruments’ high quality standard lies in their “Swissness”. They are developed and produced at our headquarters in Ennetbürgen and are individually tested before shipment according to strict quality standards in accordance with ISO 9000:2008.

Their sophisticated instrument design together with the use of high-quality optical components is the basis of the unrivalled precision of the measurement. Our TurBiScat thus achieves a resolution of 0.001 EBC with a repeatability of +/- 0.001 EBC. The reproducibility between 2 instruments is +/- 0.02 EBC with a short response time of less than two seconds (step response).

Turbidity measurement using scattered light

The TurBiScat determines turbidity with optimum color compensation using 650 nm scattered light measurement and is thus MEBAK/EBC compliant. Adapted to individual requirements and applications, the instrument covers a measuring range of 0 - 1000 EBC and can be variably configured for single or dual angle measurement. However, the significance of the turbidity measurement can be enormously increased by the dual angle measurement. Thus, in addition to conventional filtration monitoring at 90°, the additional 25° measuring angle allows the following two quality checks to be carried out:

• checking the filter construction;
• early warning of a filter break.

Integrated color measurement

Optionally, the TurBiScat can be equipped with an integrated MEBAK/EBC/ASBC compliant color measurement (430 nm) up to 50 EBC/SRM 25.4. This flexible 2 in 1 integration option is cost-advantageous in the acquisition on the one hand as well as in process connections on the other hand. A further advantage are the numerous possible applications in the brewhouse, filter cellar and pressure tank.

Low maintenance, sealless and sustainable design

The sensor head is made of corrosion resistant Hastelloy®, the window of the measuring cell consists of high-quality sapphire glass. Its integrated LED lamp consumes little power and has a service life of at least 10 years; replacement during this period is therefore completely unnecessary. This compact, sealless design can be easily and quickly installed in a Varinline® or compatible housing, allowing it to be used in virtually any process application.

Reliable and fast quality assurance

The TurbiScat has an automatic cyclical self-check which checks all functions of the instrument on a daily basis and issues a warning in case of a fault. In addition to the optical functions, all other parameters of the instrument are permanently monitored by the instrument and shown as plain text messages on the display.

Since the TurbiScat is a testing instrument, SIGRIST supplies an extra certified testing specimen with which a certification obligation can be fulfilled at any time and without external service personnel. The test is carried out using a life-long stable solid reference. Thus, neither tools nor toxic chemicals such as formazine are necessary, which is in turn beneficial to health and the environment.

SIGRIST TurBiScat monitoring and controlling filtration

Classic beer filtration consists of at least one kieselguhr filter, usually followed by a fine filter and, in larger breweries, a PVPP filter for stabilization. For measuring turbidity, the outlet of the kieselguhr filter is the most important point of installation. The highly porous kieselguhr in the filter removes a substantial amount of clouding substances from the turbid, unfiltered beer. These include particulate substances such as yeast as well as dissolved (colloidal) clouding agents such as proteins and glucans.

It is now necessary for the turbidity measurement to permanently detect even small changes in the turbidity of the filtrate in order to provide the operating personnel with information on how to control the filter. If, for example, the 90° proportion of turbidity increases, the kieselguhr mixture of coarse and fine matter has to be changed. If the 25° turbidity value increases relatively suddenly, this can mean a so-called filter break. In this case, the filter automatically switches to a closed circuit with continuing dosage of kieselguhr until the damage in the filter cake has closed. The measured values of the turbidity measurement are thus the most important indicators for the quantity and mixture of the filter aids. In general, it can be said that the 90° value covers colloidal turbidity of less than 1μm. The consumer sees this turbidity as a light veil (opalescence) in the beer which, in turn, causes complaints. The 25° value on the other hand is more sensitive to larger particles.

For 75 years and with continuous further development, the 25° forward scattered light angle has proven to be the optimal configuration to prevent disturbing reflections caused by measuring angles that are too small. This makes the 25° measurement angle best suited for particle detection.

The world's leading breweries have adopted this proven combination of 90/25° angle measurement. The TurBiScat 90/25° naturally provides these measured values color-compensated.

Would you like to learn more exciting details from our company’s history? At the same time as the upcoming BRAUWELT International issue 5, our fifth and sixth part of the 6-part series will be published simultaneously on 13th October, 2021. The focus in Part V will be on the two turbidity meters TurbiGuard and PhaseGuard, which are still part of our SIGRIST beer brewing portfolio today. The sixth and last story remains a surprise. Watch out for it!

You have not yet read Parts I, II and III? No problem, here you can go directly to the articles:

75 Years of SIGRIST: Part I: The vision of a better working world

75 Years of SIGRIST: Part II: The innovative oscillating mirror technology

75 Years of SIGRIST: Part III: The new instrument generation

SIGRIST-PHOTOMETER AG

Hofurlistrasse 1
CH-6373 Ennetbürgen
Switzerland
Phone: +41 41 624 54 75

www.photometer.com