BNO Introduction Operating principle - Nixon Flowmeters

1 The BNO series Flowmeters have been designedspecifically for high accuracy flow measurement and batch control in the liquid food industries, and conforms to the same exacting standards as our NT industrial Flowmeters so far as performance is the basic design, Nixon Flowmeters have beenaware of the particular hygienic requirements of thebrewing and dairy industries, and great care hasbeen taken to ensure the absence of crevices wherebacteria can lodge and materials used in construction ensure that nocorrosive attack occurs when in-place cleaning agentsare entirely from stainless steel, except thebearing bushes which are normally of are no seals or O rings, nor any internal screwthreads.

2 Rotors are machined from the solid, andbearing supports (hangers) are stepped in order toreduce the contact area between hanger and meterinternal ferritic stainless steel rotor revolves within a nonmagnetic housing on the outside of which is located apick off coil containing a permanent magnet. As therotor blades pass the tip of the permanent magnet,the reluctance of the magnetic circuit is changed, anda small voltage is generated in the coil. Thefrequency of the voltage is proportional toflowrate, and the total number of pulses producedrepresents total flow passed through the flowmeter may be located some considerabledistance from the associated secondary instrument,and remote flowrate indication, total flow.

3 And mostimportant remote batch control are thus CountsBBNNOOH ygienic Type Turbine FlowmeterIntroductionOperating principleAdvantagesMinimum of bacteria breeding crevicesSimple robust designEasy one circlip dismantlingStrong rotor designLong bearing lifeSteam cleaning permissibleHot detergent Sterilizing permissibleExcellent repeatability for batchingWide variety of end fittings availableA range of electronic readout instruments havebeen designed to complement our range of turbineflowmeters. Information is available on pages 1 1/2 1 1 BNO100018-1804-403301500 1 1 BNO150025-2506-552401090 1/2 1 1/2 1 BNO200045-45010-100100454 2 1 1/2 BNO3665-65014-14090400 2 1 1/2 BNO5090-90019-19033150 2 2 BNO65120-120026-2601778 3 3 For best results the flowmeter should be installed wellaway from heavy current carrying cables and withcontrol valves etc.

4 Located downstream of the length of straight pipe of bore equal to the meterinlet should be provided, preferably 10 diameters inlength, and if possible containing flow straighteningvanes at the inlet end. Turbine meters are sensitive toswirl and any pipe swirl present upstream may causea change in meter should be provided to minimise the risk ofdamage due to small solids in suspension. Metersmaybe installed in any attitude but the flow directionand mounting attitude should be advised at the orderstage if other than Flowmeters are calibrated on water at our testfacility before despatch and a calibration instructions concerning the electrical connectionsand signal cables are supplied with the handbook forthe particular electronic readout equipment beingsupplied.

5 But it is important to remember that thesignal cable screen should be earthed at one pointonly in the system to avoid earth off coils should be screwed down to the bottomof the coil well but should not be tightened by pressures are in most cases limited by the type of end fittings, and meters have been supplied to operate up to 350 densities have no appreciable affect on the accuracyof axial flow turbine meters so far as volumetric flow isconcerned. If readout is required in mass flow terms we cansupply density or temperature compensation equipment toautomatically correct for density variation.

6 All turbine metersare to some extent sensitive to viscosity changes and any likelyviscosity variation should be advised at the order stage. Highviscosity and/or low density will tend to reduce the operatingflow range over which the meter will yield the stated should be taken to avoid cavitation at the meter and a good general rule is to ensure that the static pressuredownstream is equal to at least twice the pressure drop across the flowmeter plus the vapour pressure of the up to 150 C are permissible using ourstandard pick off may be carried out by our service engineers inthe field.

7 But meters should be returned to our factorywherever possible for replacement can be effected on site by any skilledfitter and instructions will be provided on request. When requesting service visits or spares the full serial numbershould be stated, which immediately gives us access to theoriginal order files for the flow ranges given assume a liquid with viscosity1 cps and of Increase in viscosity increases theminimum linear flowrate such that overall linear range isreduced. For increased viscosities refer to Head pressure drop figures given assume a viscosity of1 cps and are the maximum estimated figures formaximum flowrate for the given meter size.

8 For lowerflowrates the pressure drop reduces as the square of theflowrate. The performance figures given above are basedon previous experience and are what we would expect toachieve on calibration. No guarantee is however givenunless specifically agreed at the order CountsHygienic Type Turbine FlowmeterBBNNOOI nstallation and useSizing tableFlow Range (Linear)Approx. K Drop (Bar) at max. flowOverall LengthEnd Fittings CountsBBNNOOP arts and materials1 Circlip302 st/stl2 Downstream Hanger316 st/stl3 Rotor with bush431 st/stlPTFE/Carbon4 Spindle316 st/stl5 Upstream Hanger316 st/stl6 Housing316 st/stl7 Coil collar316 st/stl8 Pick off coilst/stl bodyType NumberABCBNO 250805070 BNO 5001625075 BNO 10001625078 BNO 15001625080 BNO 20001557082 BNO 361556485 BNO 501657592 BNO 652169698 Allow an extra 50mm height on dimension C for pickoff coil Type Turbine CountsBBNNOOT echnical dataEnd fittingsMeasuring range10-1 Accuracy rangesmin.

9 2-20 1/minmax. 120-1200 l/minMaximum Operating temperature150 CMaximum Operating pressureLimited only bycoupling designTransmission lengthUp to 300 pre-ampPick off coilReluctance type withamphenol connector forminiature screened version availablefor hazardous locationsThe BNO range of turbine meters have beenparticularly successful in the brewing industry wherethousands of units are employed throughout Britainand abroad in keg filling operations. Several leadingbreweries have standardised on the BNO design toensure high accuracy batching and long maintenancefree operation. Nixon Flowmeters offer a flexibleapproach to design and end fittings such as RJT andtri clamp hygienic couplings can be supplied withoutany penalty in cost and delivery.

10 Special designs havebeen considered for unusual applications winebag filling, where a heavy duty design was employedto cope with continuous repetition of very Type Turbine Flowmeter1 tri clamp fittings1 CB/TS two start1 RJT fittings