FAQs for obsolete products

How do the valves in Scanivalve Modules operate?
All ZOC16, ZOC17, and DSA modules have four way valves for each sensor. Application of a control pressure causes a piston in each valve to compress an o-ring, forming an air tight seal. All of these valves are capable of, and have been tested to, a minimum of one million operations.

All ZOC 22, 23 and 33 modules also have four way valves for each sensor. These valves use inflatable bladders instead of pistons. Although the method is somewhat different, the bladders are able to form air tight seals.

What are control pressures?
Control pressures are used to switch the valves in a module to one of the standard operating modes: Zero, Operate, Calibrate, and Isolate. Electronic signals are not required to switch these valves.

How do the control pressures operate the valves?
Each module requires two or three control pressures to operate the valves, depending on the valve logic. ZOC16, ZOC17 and all DSA modules require three pressures. Two of the pressures control the normal valve modes. The third pressure controls a separate purge valve.

ZOC22, ZOC23, and ZOC33 modules also require two or three control pressures. The standard versions of these modules require two control pressures. The Duplex versions of these modules require a third control pressure to operate the Duplex valve.

The different modes of operation are obtained by applying the control pressures in a logical sequence. Truth Tables may be found in the appropriate module hardware manual that show the logic required for proper operation.

Do control pressures have to be applied at all times?
All DSA series, ZOC16, and ZOC17 modules are" normally open" valves. That is, no control pressure is required to put the module in the Operate mode. Control pressures are required to switch the valves to the other modes of operation. The control pressure used for these modules must be 85 to 105 psi depending on the pressure range of the module.

All ZOC22, ZOC23, and ZOC33 modules require a control pressure for each mode of operation. The control pressure for these modules must be 60 to 65 psi.

Is it possible to minimize the number of control pressures needed?In some cases, yes. For DSA modules, a single control pressure may be used for "Zero Calibrations" Also, CTL 1 and CTL 2 may be applied from the same source to switch the module into the Calibration mode. ZOC22, ZOC23, and ZOC33 modules must have all control pressures available.

What quality of air should be used for control pressures?
In order to prevent damage to the valves and sensors, the control pressures for all modules must be "Instrument Grade". For more information, please refer to ISA Specification ISA-S7-3.

How do I upgrade the software?
Software upgrades are available from Scanivalve Corp. A detailed upgrade procedure may be found in the DSA3200 Series Software Specification, which is also available for download from this website. For more information on updating software for these modules, contact Scanivalve Corp, Product Service Department.

I have lost my backup coefficients. What can I do?
Scanivalve Corp keeps a record of the coefficients for each module generated in the most recent calibration performed at Scanivalve Corp. These coefficients can be obtained at no charge by contacting Scanivalve Corp, Product Support Dept.

The original coefficients for any module calibrated with a customer DSM is stored in a backup folder on the DSM hard drive. In addition, the coefficients are shipped on a floppy disk as a backup. If the coefficients cannot be found, copies of the last calibration coefficients may be obtained by contacting Scanivalve Corp, Product Support Department.

How do I obtain coefficients for my modules?
Scanivalve Corp keeps a record of the coefficients for each module generated in the most recent calibration performed at Scanivalve Corp. These coefficients can be obtained at no charge by contacting Scanivalve Corp, Product Support Dept.

How do I upgrade the software?
Software upgrades are available from Scanivalve Corp. A detailed procedure may be found in the RAD3200 Manual, which is also available for download from this website. For more information on updating software for these modules, contact Scanivalve Corp, Product Service Department.

How do I upgrade the software?
Software upgrades are available from Scanivalve Corp. A detailed procedure may be found in the DSAENCL3000 Manual, which is also available for download from this website. For more information on updating software for these modules, contact Scanivalve Corp, Product Service Department.

SPC3000 Calibrator Modules
SPC3000 Calibrator Modules are obsolete. They have been replaced by the SPC4000 Calibrator.

How many pressures must be applied to the calibrator?
All servo operated calibrators require a 95 psi supply to operate the internal valves. The Servo operates from a separate servo supply.

How accurate must the control and servo pressures be?
The control supply may be 85 to 105 psi depending on the full scale pressure range of the module. The servo supply must be 3 to 10 psi greater than the full scale range of the module. The servo supply must be very well regulated.

What quality of air must be applied to the calibrators?
In order to prevent damage to the valves and secondary standard, the control and servo pressures must be "Instrument Grade". For more information, please refer to ISA Specification ISA-S7-3.

My calibrator oscillates, what do I do?
The stability of a Servo operated calibrator depends upon the servo supply input and the volume connected to the output of the calibrator. All servo operated calibrators are "tuned" at the Scanivalve Factory prior to shipment. Unless the customer installation exactly matches the Scanivalve Factory air supply, the modules may have to be re-tuned prior to use. The modules may be re-tuned by executing a "TUNE" command.

I cannot communicate with my calibrator.
All calibrators communicate with a Scanivalve Pressure Measurement System or Host computer using a RS-232 connection. The settings are: 9600 BAUD, 8 data bits, 1 stop bit, no parity. All calibrators are designed to be used in systems with multiple calibrators in a "daisy chain" configuration. Each calibrator has a unique address from 1 to 9. Commands to the calibrator must be preceded by the calibrator address. All calibrators shipped from the Scanivalve Factory have the address set to 1 unless the calibrator is part of a larger system. The address may be changed by a user by changing the setting of ADDR. For more information consult the Calibrator manual or contact Scanivalve Corp, Product Support Dept.

How often should I calibrate the module?
Calibrators with Mensor Secondary Standards DSA modules should be re-calibrated at a six month interval for the best accuracy. Calibrators with a Digiquartz Secondary Standard should be re-calibrated at six month intervals for the first year. Generally after the first year the calibration interval of Digiquartz Secondary Standards may be extended to one year.

ZOC Pressure Modules

What are the power requirements?
All ZOC modules require + 15Vdc and -15 Vdc for operation. This voltage does not need to be instrument grade. Sensor excitation voltage is developed on board the module.

How do I address the modules?
Addressing is a 4 to 6 bit address line depending on the number of sensors in the module. All address line inputs are pulled up to the +15 Vdc input.

How do I calibrate the modules?
The modules may be calibrated by applying the correct control pressure to switch the module to the Calibrate mode. Calibration pressures may be applied to all sensors from the CAL input. It is recommended that a second order polynomial be used to characterize each sensor for the best accuracy.

How often should I calibrate the modules?
ZOC pressure modules will show a considerable amount of drift unless the module is installed in a Thermal Control Unit. For best accuracy, a ZOC module should be re-zeroed before each data point. Calibration should be checked prior to taking data. Scanivalve Corp provides a utility program for customers who can perform their own calibrations. This program is called PressCal and may be downloaded from this website at no charge.

Mechanical Scanivalves/Fluid Switch Wafers
Scanivalve Corp regrets that the entire Mechanical Scanivalve product line can no longer be supported. Components for the products in this line cannot be obtained nor manufactured. The products in this line were designed prior to 1980 and obsoleted in 1995.

My Scanivalve will not step.
Scanivalves with solenoid drives require 24 Vdc at 4 to 6 amps to step.

Scanivalves with stepper motors require a step or home contact closure. These systems have opto-isolated inputs that require a pull up voltage. If this voltage is present, the power supply may be at fault.

My Scanivalve System steps, but it is very rough.
The motor driver board or the power supply board may have to be replaced.

My Scanivalve System tries to step, but it is cannot complete the step.
The motor driver board or the motor logic board may have to be replaced.

My Scanivalve cannot find Home.
Odd-Even or other encoders in Type J, D, or S Scanivalves may have to be aligned. Scanivalve systems also may need encoder re-alignments, but they could also have a failed optical diode.

How do I interface to the Scanivalve Encoder.
Encoder circuits wiring diagrams may be downloaded from the Product Information Section of this website.

How do I connect the wires on a Solenoid Drive?
Solenoid Drive wiring diagrams may be downloaded from the Product Information Section of this website.

What is the recommended Lubrication and Maintenance schedule for Scanivalves?
This information may be downloaded from the Product Information Section of this website.

What is Balance Pressure and how should it be applied?
Older Type D, Type S, and all Fluid Switch Wafers(except model W62) require balance pressure for proper operation. The balance pressure should be equal to the average input pressure. Also, input pressures should be equally distributed around the inputs to prevent very high pressures in one quadrant. If the input pressures are below ambient pressure, Balance pressure may not need to be applied unless the pressures will be greater than 3 psi below ambient. At that time a low vacuum pressure may need to be applied.

Scanivalve Digital Interface Units
Scanivalve Corp regrets that the Scanivalve Digital Interface Unit (SDIU) product line can no longer be supported. Components for the products in this line cannot be obtained nor manufactured. The products in this line were designed prior to 1985 and obsoleted in 1995.

The SDIU will not accept commands from a Host computer.
The "End of Transmission" characters stored in memory do not match the characters used by the Host Computer.

The SDIU loses the setup when powered down.
The battery in the Non-volatile RAM chip has failed. The chip(Dallas DS1220) must be replaced.

The display is flickering.
The power supply voltage(s) is(are) too low.