What is the minimum wrap?
Typically, the minimum recommended wrap angle around a load cell is 30-degrees, but this can vary based on material type, line speed, and web tension. For best results, the web needs to maintain continuous contact with the TNT roll. A shallow wrap angle combined with higher web speeds and low tension can allow air to be trapped between the web and the tension roll, and the signal from the load cell may be inaccurate. However, there are circumstances where a shallow wrap angle can be a benefit, particularly if the tension is very high, and may exceed load cell capacity with a greater wrap angle. It is always best to consult a Montalvo Applications Specialist to ensure best results.
Can I use in Hazardous Areas?
Yes, the TNT can be used in a hazardous area, provided they are connected to the appropriate barrier blocks to limit the current in the affected area. Montalvo offers a series of barrier blocks approved for use in Class 1 Division 1 Hazardous Areas. Please consult a Montalvo Applications Specialist for assistance with these applications.
Can these be washed down?
The TNT load cells are not recommended for use in an area that requires wash-down procedures. They are rated IP54, which provides protection from the amount of dust that would interfere with the operation of the equipment, and protection from splashed water.
Can they be used in Clean Room Environments?
The TNT load cells are perfectly appropriate for use in clean-room environments as the bearing areas are sealed, and they emit no dust or fumes.
Are these drop in replacements for “Brand X”
The TNT load cells can be configured in many ways with respect to mounting, shaft length, roll face length and diameter, load ratings. They can be specified to fit where any idler roll or load cell roll are currently used.
Will these work with “Brand X” Controllers/Amplifiers?
The TNT load cells require 5 volts of DC excitation, and provide an output from 0-250mV. They may be used with any amplifier that meets these requirements, but it is recommended that they be used with a Montalvo amplifier to ensure proper function. Please consult a Montalvo Applications Specialist if you have any questions regarding proper amplification.
Is the TNT intrinsically safe?
On its own, the TNT load cell is not intrinsically safe. The load cell must be connected to the appropriate Barrier Block system, approved for the proposed load cell location. Please contact a Montalvo Applications Specialist for assistance with these applications.
What excitation voltage does the TNT use?
The TNT load cells require 5 VDC excitation.
What is the maximum tension I can measure?
Maximum tension is determined by several factors including web width, wrap angle around the TNT load cell roll and the load cell load rating. Careful analysis of the application must be made to ensure the load cell can measure the expected tension loads. Montalvo TNT load cells are available with load ratings up to 200-lbs. Please consult a Montalvo Applications Specialist to assist with the proper sizing for your application.
What is the lowest/lightest tension I can control to?
Montalvo TNT load cells can repeatedly and accurately measure and control to less than 2% of maximum stated load.
How do I determine what length my roller needs to be?
Proper sizing for the installation requires at least two critical measurements: Inside Frame-to-Frame measurement, and the roll face length of the existing idler rolls. Please consult the TNT Tension Sensing Roller Request Worksheet & Datasheet (644 KB) or contact a Montalvo Application Specialist for additional assistance.
Can I have special shaft ends?
The shaft ends can be custom-configured to match existing idler roll specifications for simple, drop-in replacement, or for any requirements necessary to ensure proper installation. Typical configurations include drilled and tapped holes in the end (standard or metric) and wrench flats machined onto the shaft to facilitate holding the shaft for proper load direction orientation while tightening the mounting bolts.
How do I install the TNT?
The TNT load cell is easy to mount in its basic configuration. It typically replaces an existing idler roll, and mounts to the machine side frame, utilizing existing mounting holes. The ends of the shaft can be specified to suit just about any installation requirements. It can also be mounted in pillow-block brackets to facilitate mounting on a horizontal surface.
How do I calibrate my TNT?
The calibration procedure for the TNT load cell is the same as for just about any other load cell. Typically the load cell amplifier circuit is zeroed, with no load on the load cell at all, then a known calibration weight is suspended from a rope or a strap, following the typical web path. Then the amplifier circuit is adjusted to provide the appropriate output for the given calibration weight. It is recommended that a calibration weight that represents at least 25% of maximum web tension is used. If the TNT load cell is used in conjunction with the Montalvo A4 Digital Load Cell Amplifier, simple push-button calibration can be performed using 10% of the load cell load rating for the calibration weight. Please refer to the calibration procedures for either the M-32XX series of Montalvo Load Cell Amplifiers or the A4 Digital Amplifier for more details.
How do I test gage resistance for troubleshooting?
The TNT load cell utilizes Strain Gage technology in order to sense the web tension and tension changes. In the rare event that the load cell signal is in question, it is possible to measure the gage resistance to make sure it is in the correct range for proper operation. The gages are rated for a nominal resistance under no load at 90 to 120 ohms. To check the gage resistance, disconnect the load cell cable from the amplifier/controller.
Typical load cell cable color codes are as follows:
Black: negative load cell excitation
Red/Brown: positive load cell excitation
White: positive load cell signal
Green/Blue: negative load cell signal
With an Ohm Meter, measure the resistance between: Black and White wires – should be between 90-120 ohms
Needs additional information.
How do I invert the load cell signal?
There are two ways to invert the load cell signal. The first way is to rotate the mounting shaft 180 degrees. The other is to switch the green/blue wire and the white wire at the amplifier/controller.
How do I test operation?
Provided the calibration has been successfully completed, testing the load cell function can be done by having someone push on the TNT roll in the direction of force due to web tension, and monitor the tension change. Alternatively, you could use the web to apply a force to the load cell, and monitor the output change from the amplifier.
