GRAVITROL DENSITY ANALYZER Mark 1V Model 1373 For Measurement or Control of Density of Liquids or Slurries

This analyzer, first introduced in 1954, has been successfully applied to CI great many industrial density

measurement problems. It provides the most practical method of measuring the density of a slurry and, of

course. is equally suitable for use with clean liquids. The Mark IV embodles ci number of major improvements

as a result of field experience:

`Robust construction, reliable, simple to maintain wit/? CI minimum of servicing

*Temperature compensation to maximum of 1OOa/o of the working span

*Fore balance transmission signals, linearly related to the density span

*Recalibration on site for any density span within the range of the meter,

*Higher sensi*ivity with long term stability

*Sample loop easily cleaned on site

WORKING PRINCIPLE

The process liquid flows through the tube loop [A) pivoted on flexures (BJ about an VA,> which passes

through the flexible connectors [C). The weight of the tube loop and contents is transferred to a weigh-

beam (0) and counterpoised by the balance weights (E) which are adjustable along the beam. A change in

the density of the process liquid produces a directly proportional change in force on the weigh~beom. This force

is measured bv a force balance transmission svstem.

I ANALYTICAL INSTRUMENTS FOR CONTINUOUS PROCESSES I

TRANSMISSION SYSTEMS

Two systems ore available and provide a choice of a pneumatic or an electrical output signal, linearly related to the density range. A density change con be measured in liquids or slurries with o nominal density between 0.4 and 2.5 g/ml.

The pneumatic transmission is of the force balance type with nozzle-flapper detection and bellows feed- bock, providing an output signal of 3-15 p.s.i.g. The density span is adiustable between 0.025 and 0.25 g/ml or alternatively, with o larger feedbock bellows, between 0.05 and 0.5 g/ml. The air supply must be capable of delivering 30 cu. ft./hr. of clean dry air at a regulated pressure of 20 p.s.i.g. The electrical transmission is also of the force balance type with capacitive detection and pot coil feedback. Two DC. output sign& ore available, both of which have o live zero.

Output Signak Maximum Output Maximum Output MA D.C. Circuit Resistance Circuit Resistance Without Repeater With Repeater Board. Ohms. Board. Ohms. o-10 1000 3000 4.20 600 1500

With electrical transmission only, the density span is adiustable between 0.01 and 0.2 g/ml or alterna- tively, between 0.05 and 0.3 g/ml. The power supply must be single-phase, 50 or 60 c/s, at either 1 lo-120 or 200.250 volts.

PERFORMANCE Sensitivity or discrimination o!i"/o of span Repeatability &0.25% of span Linearity r+O.25% of span Linearity with temperature compensation %0.5% of span

Accuracy for spans of 0.03 to 0.5 g/ml over the working pressure range 21% of span

For spans between 0.01 and 0.03 g/ml, the accuracy is proportional to the span and pressure range and is within %3% of o 0.01 g/ml span over the whole pressure range of O-150 p.s.i.g. Under atmospheric pressure conditions, the maximum error of true density measurements is +1.5x of o 0.01 g/ml span or -CO.00015 g/ml. An increase in the process liquid temperature causes a change of approximately 0.000007 g/ml per "C., but the instrument is so designed that the effect of ambient temperature change is negligible. Calibration during m,anufacture assures that changes in process pressure do not give rise to false density signals and that the instrument leaves the factory, set for the specified density range. However, readjustment on site to a different range is o simple operation with the aid of weights provided.

CONTACT MATERIALS

The standard tube loop and flexible connectors are made from 316 stainless steel and ore suitable for use with any density range available, from either transmission system, up to o maximum working pressure of 150 p.s.i.g. ond 300°F. temperature.

P.T.F.E., butyl, silicone and viton rubber flexible connectors con be used with contact materials such os nickel, monel, glass, Korbate, stainless steel or stainless steel lined w,ith P.V.C. or ebonite, but with these connectors, the smallest density span available is 0.05 g/ml. At ambient temperature, the maximum working pressure is 40 p.s.i.g. with rubber connectors or 60 p.s.i.g. with P.T.F.E.

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Gmvitrol with Pneumatic Tmnsmirsion INSTALLATION

As the density meter will de- tect CI weight change of 1 part in 100,000, the operational en- vironment is of considerable importance in obtaining opti- mum performance. Each appli- cation should be considered in detail since careful installation will assure accurate, trouble-free operation. Standard tube loop bores of 0.9" and 1.4" CI r c available through which all, or part of the process liquid can be passed. Flange connections are normally 1" or 1 %" ASA. lSO# RF. To assure that no stress or vibration is transmitted to the instrument, it is recom- mended that flexible tubing be used for piping between pro- cess line and analyzer, or at least for a short distance at the CWl+Zer.

AIR AND GAS

Air and gas entrainment must be minimized for accurate measurement since the instrument operates on a volumetric weight principle.

Since the meter measures the density of the contents in the sample loop, measurement will be unaffected by particle size, provided that the particles are small in comparison with the size of the bore. A slurry must be circulated through the tube loop at 01 sufficient rate to prevent the deposition of solids. The recommended velocity for slurries is approximately 7 ft./set., equivalent to CI flow rate of 700 gal/h. in a 0.9" bore tube loop, or 1,700 gal/hr. for a 1.4" bore.

For clean liquids, a high velocity is only required on start up to clear the air from the tube loop. The recommended velocity is 3 ft/sec., 300 gal/hr. for a 0.9" bore, or 750 gal/hr. for a 1.4" bore. Once the air has been cleared from the tube loop, the velocity moy be decreased, but the mean density of the tube loop contents will then change more slowly.

For cleaning purposes, the density meter may be flushed with any solvent that does not affect the wetted

parts.

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TEMPERATURE COMPENSATION

One com~mon density meter application is the measurement or control of the concentration of a solution which requires the suppression of density signals caused entirely by process temperature change. This sup- pression or compensation is achieved by applying c1 force change to the measuring system which is equal and opposite to the force change caused by temperature effects. The maximum compensation available is for a temperature change producing a change in density equal to the span of the instrument.

Desired Gravitrol Span > or = T compensation x T,

Tcompensation I = Maximum temperature span possible on compensating transm.iiter (reference temperature must be included in span]

T, = coefficient of thermal expansion For example: For an instrument that has a density span of 0.05 g/m,l, metering CI liquid with a coefficient of thermal expansion of 0.5 x 10-S per "C., compensation can be applied for a maximum temperature change of 100°C.

The temperature com,pensation unit is an optional addition to the standard instrument. It is available for linear or non-linear coefficients in pneumatic signal units, but linear only in electric.

TEMPERATURE LAGGING

For process fluids with a high pour point temperature, the Gravitrol may be supplied with internal heat- ing coils to develop an adequate temperature in the loop to keep sample liquid.

AUTOMATIC CONTROL OF DENSITY

The Gravitrol Density Analyzer Mark 4, designed for continuous operation, is robust and requires an absolute minimum of servicing. Excellent results have been obtained with automatic density control systems due to the high speed of response and adiustable range of this instrument.

SPECIFICATIONS

Tube diameters: 1" (std.), 1%"

Materials of construction: 316 s. s. (std.), nickel, monel, glass, karbote or s. s. lined with PVC or ebonite

Flexible connectors: s. s., monel, P.T.F.E., nickel, butyl, silicone and viton rubber.

Process connections: Flanged ASA 150# R.F. (std.)

Span: Pneumatic output (3-15 psi) 0.025 to 0.25 gm/ml or 0.05 to 0.5 Electrical output (4-20 MA DC or O-10 MA DC) 0.01 to 0.20 gm/ml or 0.05 to 0.3 gm/ml

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Measureable density: 0.4 to 2.5 gm/ml Outputs: 3-15 psi, 4-20 MA DC or O-10 MA DC Temperature limits: To 390°F. dependent on flexible connectors Pressure limits: To 150 psi dependent on flexible connnctors Sensitivity or discrimination: 0.5% of span Accuracy: 1 % of span for spans of 0.03 to 0.5 gm/mI Temperature compensation: To 100% of span Minimum recommended flow rates through tube: clear fluids, 300 gph; slurries, 700 gph for nominal 1" tube Net weight: 270 Ibs. (approximately) Gross weight: 500 Ibs. (approximately) Box dimensions for shipping: Approx. 62" x 51" x 25"

Grovitrol with Electrical Tmnsmisrion and 1%" Sample Loop

The reputation which the GRAVITROL rapidly gained for ruggedness and reliability resulted in inquiries from CI wide cross-section of industry, ranging from meat extract manufacture to the processing of asbestos/ rubber/cement slurries and from the treatment of gold-bearing ores to the control of evaporation rates in the manufacture of condensed milk.

The need for versatility combined with high accuracy and increased sensitivity has led to constant im- provements, both in design and performance. The Mark 4 Density Analyzer has been engineered to incorpor- ate the knowledge gained over many years of experience from the diverse requirements of customers. The GRAVITROL is capable of long years of service under arduous plant conditions, maintaining laboratory standards of accuracy and sensitivity with minimum of attention.

The list that follows gives a cross-section of materials at present being handled. If your application is one which is not listed, please do not hesitate to contact us on your requirements.

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ACIDS AND STRONG ALKALIS Acids Adipic Acid Alkyl/Benzene/Sulphonic Acid Hydrochloric Acid Hydrochloric/Hydrofluoric Acids Nitric Acid OlfSJITl Phenoxv Acetic Acid Phosphoric Acid Spin Acid Sulphuric Acid

Alkalis Caustic Lye Potassium Hydroxide Sodium Hydroxide Sulphite (Black) Liquor (Note: The above acids and alkalis ore being m~easured under the following variables:- Concentrations 10% to 100% Temperatures ______ 0°C to 100°C Pressures ____.._..... up to 100 p5i.g.)

BRiWERlES AND DlSTlLLERlES Eeer Fermentation Products Grain Spirit Lager stout Whisky Wart (Beer) Yeast Extract Liquor

CHEMICAL AND GENERAL INDUSTRIAL PRODUCTS Dense Slurries Aluminum Powder/Methyloted Spirit Brine Crystal Magma Detergent Slurries Glass Fibre/Resin Latex/Soap Magnesia Milk of Lime Nitro-Cellulose Liquids and light Slurries Acetone Alky/Benzene/Oleum Aluminum Sulphate Ammonia Liquor Ammonium Nitrate Ammonium Sulphote Chlorinated Brine Chlorinated Hydrocarbons Dem0walized Water Emulsion Paint Ethyl Chloride Ferrous Sulphate Heavy Water [Nuclear) Hexamethylene/Diamine/SaIt Hydrogen Peroxide llmenite Sulphuric Acid Liquid Cordite Lithium Chloride Ohm Benzene Organic Acid Sodium Silicate Titanium Hydrote/Sulph. Acid Titanium Oxides

MILK AND DAIRY PRODUCTS Condensed Milk (Sweetened) Evaporated Milk Milk M,ilk Skim Whey Liquor (Milk Sugar)

MINING AND MINERAL SLURRIES Alkaline Arsenic Solution Blast Furnace Slag Cement China Clay Clay Coal Dust Coal Washery Water copper Ore Flotation Media Gold Ore Lead Ore Mineral Pulp Oil Well Drilling Mud Organic Tin Raw Coal Rouge OIL REFINERY AND LlQUiD FUEL PRODUCTS Butanol Crude Oil Diesel Oil Ethanol Ethylene Ethvlene Oxide Gas Oil Heovv & Liaht Fuel Oils Hea"; & LGht Lube Oils Heavy Hydrocarbons KZ30Wle Light Distillates Methanol Naphtha Octonol Straight Run Gasoline Tetra/Methyl/Lead/To!uene Wax/Lube Oil White Spirit

SOFT DRINKS, EXTRACTS, CONFECTIONERY, ETC. Citric Acid Fruit Juices G&tine Glycerine Liauid Coffee IConcentrate Liquid Starch Lemonade, etc. Meat Extracts sweet Water

SUGAR REFINING AND PROCESSWIG Beet Sugar Juice Diffusion Juice GIUCOS? Molasses Saccharinate Sugar Liquor sugar Syrup Thick Sugar Juice

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