Instrotech Product Listings



Grid View List View Sorting: Normal Sorting: Price Low to High Sorting: Price High to Low Sorting: New Arrivals Sorting: Brand A-Z Sorting: Brand Z-A

Keller Series 21PY

sku Product SKU:  KEL-21PYs

Ultramodern welding techniques and advances in the miniaturization of electronic circuits now make it possible to manufacture a pre-insulated, piezoresistive micro-transmitter with properties that were no more than a dream 10 years ago.

The circuit is based on the PromComp principle which KELLER offered in a separate version as a laboratory device 20 years ago when it attained accuracy of 0,1 %FS over a temperature range of 100 K. In those days the electronic circuitry was the size of a cigar box, but now it can be accommodated on a print that is a mere 12 mm in diameter.

Although this digital component is only slightly more expensive to produce than an analog circuit, it allows a piezoresistive sensor to be calibrated to an accuracy of 0,5 %FS over a potential temperature range of 100 K.

A temperature sensor divides the temperature range into fields with a width of 1,5 K each. Two values are assigned to each field in an EEPROM: one value for the zero point and another for the amplification, determined by mathematical interpolation in the calibration process. During operation, the corresponding values are ‚switched in’ at the relevant temperatures. The electronics make it possible to assign up to 120 fields so that a temperature range of 180 K can be covered. The 100 K restriction for series 21 PY is due to the sensor

This means that more or less any temperature can be the ‚calibration temperature’ for these transmitters. Calibration and temperature errors within a temperature field are within ± 0,2 %FS. The remainder of the error bandwidth of ± 0,5 %FS can be attributed to linearity and stability errors. So it’s goodbye to the days when sensor engineers had to struggle every day with TKN (zero point) and TKG (gain/amplification) problems.

The 21 PY product line is outstanding due to its extreme ruggedness towards electromagnetic fields. The limits of the CE standard are undercut by a factor of up to 10 with conducted and radiated fields, thus making this product ideal for use in harsh industrial environments.

ZAR 0,0000


Keller Series 33X

sku Product SKU:  KEL-33Xs

Digital Output of Transmitter:

This high precision of 0,01 %FS is available as an option (the standard Series 33 X has an accuracy of 0,05 %FS). These Series are based on the stable, floating piezoresisitive transducer and the newly developed XEMICS micro-processor with integrated 16 bit A/D converter. Temperature dependencies and non-linearities of the sensor are mathematically compensated.

Transmitter with Analog Output:

Integrated in the XEMICS processor is a D/A converter of 16 bit for analog signal outputs of 4…20 mA or 0…10 V. The output rate is 400 Hz. The accuracy is diminished by this converting process by 0,05 %FS. The digital output is available on all transmitters with analog output.


With the KELLER software READ30 and PROG 30, a RS485 converter (i.e. K102 or K107 from KELLER) and a PC, the pressure can be displayed, the units changed, a new gain or zero set. The analog output can be set to any range within the compensated range.

Accuracy and Precision

“Accuracy” is an absolute term, “Precision” a relative term. Dead weight testers are primary standards for pressure, where the pressure is defined by the primary values of mass, length and time. Highest class primary standards in national laboratories indicate the uncertainty of their pressure references with 70 to 90 ppM or close to 0,01%. Commercial dead weight testers as used in our facilities to calibrate the transmitters indicate an uncertainty or accuracy of 0,025%. Below these levels, KELLER use the expression “Precision” as the ability of a pressure transmitter to be at each pressure point within 0.01 %FS relative to these commercial standards. The transmitter’s full-scale output can be set up to match any standard of your choice by correcting the gain with the PROG30 software.

ZAR 0,0000


Keller Series PRD-33X

sku Product SKU:  KEL-PRD-33Xs

The Series PRD-33 X was developed for applications that require a high accuracy differential pressure measurement together with high overload resistance in differential pressure ranges as low as 350 mbar.

The Series PRD-33 X is the result of ongoing development of the KELLER PD-33 X differential pressure transmitter. Thanks to a second integrated pressure sensor, the line, or common mode, pressure can now be measured along with the differential pressure, resulting in several notable features not found in traditional differential pressure transmitters.

For example, compensation for line pressure effect is now accomplished during factory calibration. Moreover, both differential and line (absolute) pressure may be read by the user. In addition, the PRD-33 X features high differential overload resistance; e.g., ± 35 bar with a differential measuring range of only 350 mbar (100:1).

The internal differential pressure sensor element is isolated from the High (+) side media by a compliant stainless steel diaphragm, while the Low (-) side media impinges directly on the back side of the silicon measuring cell. Also isolated from the High (+) side media is the line (absolute) pressure sensor. The floating sensor assembly guarantees maximum decoupling from external mechanical forces.

Another notable feature of the Series PRD-33 X is the robust digital RS485 bi-directional communication interface. Information such as serial number, pressure range, filter settings and process values for both differential and line (absolute) pressures and their temperatures are easily obtained.

This combination of features enables certain measurements not possible with traditional differential pressure transmitters. For example, filling levels in liquefied gas storage tanks, including oxygen, nitrogen, carbon dioxide and argon can now be measured safely, accurately and at reasonable cost.

ZAR 0,0000

{{minicart.wishlist.length}} {{minicart.cartList.length}}
You have no items in your shopping cart.
You have 1 item in your shopping cart.
{{multiCartItemsStr.replace('[COUNT]', minicart.cartList.length)}}
  • {{itemVariant.VariantHasText ? (itemVariant.VariantName + ': ' + itemVariant.VariantText) : (itemVariant.VariantGroup + ': ' + itemVariant.VariantName)}}
Total: {{cartItem.UnitCost * cartItem.Quantity | currency : 'R' : 2}}
Qty: {{cartItem.Quantity | number : 2}}

Item Qty Total
{{cartItem.ProductName}} {{cartItem.ProductName}}
SKU: {{cartItem.ProductSku}}
{{cartItem.Quantity | number : 2}} x {{cartItem.UnitCost | currency : 'R' : 2}}
{{cartItem.UnitCost * cartItem.Quantity | currency : 'R' : 2}}
  • {{itemVariant.VariantHasText ? (itemVariant.VariantName + ': ' + itemVariant.VariantText) : (itemVariant.VariantGroup + ': ' + itemVariant.VariantName)}}
You have no items in your shopping cart.
Subtotal {{minicart.cartTotals.SubTotal | currency : 'R' : 2}}
Image Item Qty Total
{{cartItem.ProductName}} {{cartItem.ProductName}}
SKU: {{cartItem.ProductSku}}
{{cartItem.Quantity | number : 2}} x {{cartItem.UnitCost | currency : 'R' : 2}}
{{cartItem.UnitCost * cartItem.Quantity | currency : 'R' : 2}}
  • {{itemVariant.VariantHasText ? (itemVariant.VariantName + ': ' + itemVariant.VariantText) : (itemVariant.VariantGroup + ': ' + itemVariant.VariantName)}}
You have no items in your shopping cart.
Description Created
{{savedCart.Description}} {{savedCart.CreateDate | date : 'yyyy-MM-dd h:mm a'}}
SKU Product Name Unit Cost Qty Line Total
{{cartItem.ProductSku}} {{cartItem.ProductName}} {{cartItem.UnitCost | currency : 'R' : 2}} {{cartItem.Quantity | number : 2}} {{cartItem.UnitCost * cartItem.Quantity | currency : 'R' : 2}}
  • {{itemVariant.VariantHasText ? (itemVariant.VariantName + ': ' + itemVariant.VariantText) : (itemVariant.VariantGroup + ': ' + itemVariant.VariantName)}}
You have no items in your saved shopping cart.
You have no items in your wishlist.
Status Order No. Order Date Ship To Order Total Pay Total Balance
Bill Me Later Open Ready To Ship Shipped Picked Up Cancelled Incomplete On Hold Back Ordered Returned {{order.Status}}
{{order.OrderID}} {{order.OrderDate | date : 'yyyy-MM-dd'}} {{order.ShipFirstName}} {{order.ShipLastName}}, {{order.ShipAddress1}} {{order.ShipAddress2}}, {{order.ShipCity}}, {{order.ShipState}} {{order.ShipZipcode}} {{order.GrandTotal | currency : 'R' : 2}} {{order.PayTotal | currency : 'R' : 2}} {{order.GrandTotal - order.PayTotal | currency : 'R' : 2}}