TRUECAP® MK-2 RF CAPACITANCE Level Probe
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TrueCap® RF capacitance sensors offer effective point level indication with excellent reliability and advanced features. Monitor’s complete line, featuring models MK-2 and MK-2e, provides you with the most practical solution for your application...from a feature-rich version to a cost-conscious version. Monitor’s RF capacitance probes are designed to provide a high level of sensitivity, stability and durability for powder and bulk solids applications, as well as liquid and slurry applications. Monitor’s two-year warranty stands behind every TrueCap sensor.
Principle of Operation
A radio frequency is applied to the probe and is continually analyzed to determine the influence caused by the surrounding environment. As material contacts the probe, the radio frequency shifts indicating an increase in capacitance (C). The active probe of the unit and the vessel’s wall make up the two plates (A=area) of a capacitor which are separated by a fixed distance (d). The probe’s insulator and surrounding air provide the dielectric material (with dielectric constant “K”). As the air (K=1.0) is displaced with any other material (K > 1.0), the capacitance effect (C) is enhanced, thereby changing the application’s impedance. This influence is measured within the circuitry and compared to a reference established by the sensitivity setting. The setting determines how much influence must be present before the output changes. The driven shield section of the probe enables the circuitry to ignore product build-up on the probe that would otherwise cause false sensing.
The driven shield is activated with the same radio frequency potential as the sensing probe. Since current can not flow between identical potentials, the driven shield blocks current flow from the active probe to the vessel wall through the material build-up, thereby eliminating the sensing of the material build-up.
Applications
TrueCap® RF capacitance point level sensors are versatile devices providing high and low level readings in bins, silos, tanks, hoppers, and other vessels. TrueCap’s superior sensitivity range allows users to properly adjust units to meet the needs of a wide variety of applications. Whether your application is for a powder, liquid, granular solid, or viscous material, the TrueCap product line offers the right solution.
Typical Applications include, but are not limited to: |
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Feed / Grain |
Chemicals |
Pellets |
Plastics |
Liquids |
Pharmaceuticals |
Rubber |
Wastewater |
Sand |
Food Ingredients |
Slurries |
Cement |
Powders |
Paint & Coatings |
Coal |
Granular Solids |
Oils |
Paper Pulp |
Features
The TrueCap® Model MK-2 RF capacitance point level sensor is a proven problem solver used to ensure maximum performance and reliability, minimizing downtime of operations. |
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Micro-controller based for maximum reliability & performance |
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Push-button calibration, sensitivity selection & self-test |
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Automatic temperature compensation for unmatched calibration stability |
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Superior 0.5 pF sensitivity ensures reliability |
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Build-up immunity helps eliminate false signals |
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High intensity LED indicating light (Ordinary location sensors only) |
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Universal power supply minimizes versions |
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Available hazardous location approvals with intrinsic safety |
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Model Selection
(Comparing the Model MK-2 and MK-2e)
Monitor offers the market an unmatched selection of RF Capacitance point level sensors. Several factors should be considered when selecting the proper TrueCap® RF capacitance point level sensor.
EASE OF CALIBRATION
Many applications are well served by the manual calibration of the MK-2e, but only the MK-2 offers the extraordinary convenience of push-button calibration, sensitivity and self-test. VARYING
TEMPERATURES
It is important that the calibration of a probe remains stable during swings in the process and ambient temperatures. The MK-2 automatically adjusts its calibration to account for temperature changes providing maximum reliability.
CHANGING CONTENTS/CHARACTERISTICS
TrueCap sensors can be calibrated to the material with the lowest dielectric constant (usually the driest material) in order to sense all products which could enter the bin. However, sometimes the need for re-calibration is unavoidable, making the MK-2 with push-button calibration and an available remote calibration module the best choice.
HEAVY MATERIALS & TIGHT AREAS
Some applications require compact, sturdy probes for heavy materials or confined spaces. The MK-2 and MK-2e offer a stub probe for extra durability for heavy products and a compact design for tight areas. Both models also use heavy duty 3/8 inch (9.5 mm) diameter probes. SOLIDS All TrueCap sensors can sense solid materials, but be careful to also look at all application parameters.
MATERIAL COATING/BUILD-UP
Many liquids, slurries and sticky bulk solids tend to cling to probes. Product build-up immunity through a driven shield design is a must. The MK-2 and MK-2e provide product build-up immunity and can typically be used with these materials. HIGH VIBRATION When locating sensors near vibrators, bin dischargers or other vibrating equipment, the split architecture version is recommended.
UNIVERSAL POWER SUPPLY
Minimizing the number of variations can maximize value for OEMs and product resellers. The MK-2 is the only TrueCap sensor that provides this capability. NEED FOR VISUAL INDICATION Both the MK-2 and the MK-2e are provided with a high intensity LED indicator on the housing (Ordinary location integral sensors only).
HAZARDOUS LOCATIONS
The MK-2 and MK-2e are available approved for Class I and Class II hazardous locations. See “Specifications” for details.
HIGH TEMPERATURE
For applications up to 450°F, (232°C) the MK-2 and MK-2e offer stainless steel mounting connections which act as thermal barriers and a split architecture version which completely removes the electronics from the process.
LARGE PARTICLES
Large particles can leave air gaps which could lead to inaccurate readings. However, smaller particles and fines usually fill in the gaps.
APPLICATION |
MK-2 |
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Ease of Calibration |
Best |
Fair |
Calibration Location |
Best |
Good |
Varying Temperatures |
Best |
Good |
Changing Contents/Characteristics |
Best |
Good |
Heavy Materials & Tight Areas |
Good |
Good |
Solids |
Best |
Good |
Material Coating/Build-Up |
Best |
Good |
High Vibration |
Best |
Best |
Need for Visual Indication |
Best |
Best |
Hazardous Locations |
Best |
Best |
High Temperature |
Good |
Good |
Large Particles |
Good |
Good |
Options
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HAZARDOUS APPROVALS |
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Accessories
MOUNTING PLATES
Painted carbon steel or stainless steel mounting plates eliminate the need to weld a mounting coupling to the vessel.
PART # DESCRIPTION
1-0101 Mounting Plate, half coupling, CS, for 1-1/4” NPT
1-0112 Mounting Plate, half coupling, SS, for 1-1/4” NPT
1-3316 Mounting Plate, heavy duty alum., for 1-1/4” NPT
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PROBE EXTENSIONS
Rigid probe extensions with solid or flexible couplings easily extend the sensing point to a desired distance from any top-mounted TrueCap® probe.
Click Here for Reference on How to Determine Overall Insertion Length for Customer Specified Legnths
PART # DESCRIPTION
11-0151-0 Solid Coupling, Customer Specified Length (Note 1)
11-0151-8 Solid Coupling, 8” (203mm) length
11-0151-12 Solid Coupling 12” (305mm) length
11-0151-20 Solid Coupling 20” (508mm) length
11-0151-32 Solid Coupling 32” (813mm) length
11-0151-44 Solid Coupling 44” (1118mm) length
11-0060 Solid Coupling Adapter (Probe extension to be provided by customer.)
11-0152-0 Flex Coupling, Customer Specified Length (Note 2)
11-0152-8 Flex Coupling, 8” (203mm) length
11-0152-12 Flex Coupling, 12” (305mm) length
11-0152-20 Flex Coupling, 20” (508mm) length
11-0152-32 Flex Coupling, 32” (813mm) length
11-0152-44 Flex Coupling, 44” (1118mm) length
11-0056 Flex Coupling Adapter (Probe extension to be provided by customer.)
Note:
1 Max Length = 44” (1118mm)
2 Max Length = 72” (1829mm) For longer lengths, upgrade to cable version.
Note:
Probe extensions listed below are to be added to the the standard Ryton® (or equiv.) or Nylon MK-2
probes. A standard probe is 16” (406mm) in length.
Example: A standard probe ordered with an 11-0151-20 will provide 16” + 20” = 36” (406mm + 508mm =
914mm) of overall insertion length. A Probe Extension is shipped as a separate item to be easily
attached with the roll pin provided.
Click Here for Reference on How to Determine Overall Insertion Length for Customer Specified Legnths
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QUICK-CONNECT TRI-CLAMP ACCESSORIES
Accessories to go with the quick-connect tri-clamp version of the TrueCap® include:
PART # DESCRIPTION
#11-3017: Tri-clamp, 1-1/2", 304SS
#11-3007: Ferrule, 1", 316SS
#11-2007: Gasket, White, Viton®
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REMOTE CALIBRATION MODULE
Part # 11-8005 has been discontinued.
Probe Variations
Dimensions are shown in inches with millimeter equivalent in brackets.
STANDARD
PROBE |
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STUB
PROBE |
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CABLE
EXTENSION PROBE
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PIPE
EXTENSION/LAGGED HOUSING
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Specifications
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* Influenced by mounting, material thermal conductivity and ambient temperature.
** Hazardous location approvals on units with Pipe Extension or Lagged Probes with integral electronics/probe are CSA(US/C) Class II Groups E, F & G (SS version ONLY. Hazardous location approvals are not available on the galvanized version). Hazardous location approvals for Split Architecture remote electronics are Class II, Groups E, F & G. All probe versions, except the galvanized version of the pipe extension or lagged probe unit, are Class I Groups C & D, Class II Groups E, F & G and Intrinsically Safe.
Probe Specifications
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Ryton® - Trademark of Phillips Chemical Co.
Teflon® - Trademark of DuPont Chemical Co.