FAQ – Frequently Asked Questions

Valve Communication and Control (ValavePoint) FAQ’s

1.) How do I bench test a StoneL SST sensor?
Answer: Since these are solid state sensors, you will not be able to bench test them by measuring continuity. Solid state sensors need power to operate. Here is a diagram that shows the test circuit. The IMO for the product contains the complete test procedure.

2.) I am replacing a contact type switch unit with a StoneL model that has SST solid state sensors, how do the sensors get wired into my control system?
Answer: 2-wire solid state sensors electrically act like a SPST contact type switch. You would connect the wire that was connected to the common of the contact switch to the Common (C) terminal of the SST sensor and the wire from the NO contact of the switch to the NO terminal of the SST sensor. Here is a diagram that shows the basic circuit. As with a contact type switch, no additional power is required other than what is provided by the control system input card.

3.) I would like to rebuild my Axiom Spool valve, do you sell rebuild kits? Do you have a video showing installation?
Answer: Yes, we sell rebuild kits and they are easy to install. See the available kits on the “downloads” tab for each of the Axiom platform pages. To make it easier to install these rebuild kits, we have produced a short video showing the installation procedure. See the video here.

4.) My spec calls for 2x DPDT switches. I don’t find any options that meet my voltage / current requirements, what can I use?
Answer: StoneL does offer mechanical DPDT switches. However for applications that are not appropriate for mechanical switches or applications where reliability and long cycle life are important, we would recommend using 4x SPDT switches. The SPDT Reed-Type proximity switches have much longer cycle life and reliability than mechanical switches, and 4x SPDT has the same contacts as 2x DPDT.

5.) What switches should I select for intrinsically safe application?
Answer: StoneL has many options for these applications. If you application calls for a solenoid valve as well, consider the Axiom model, AMI44…….. Other options exist in the Eclipse, Quartz and Prism platforms. See the model selection guides for each platform for applicable options. Here is a diagram showing typical intrinsically safe wiring schematics.

6.) My spec calls for a 24vdc intrinsic safety coil. StoneL only offers a 12vdc intrinsic safety coils, why is that?
Answer: IS specs for solenoids are commonly expressed in terms of the voltage that is applied to the safe area side of the barrier.(non-hazardous area) In fact the barriers have inherent resistance and that in conjunction with the coil resistance give you a voltage drop across the barrier. This is usually about half of what the voltage is that is applied to the non-classified side of the barrier (if barrier end-to-end resistance and coil resistance are equal).

You may have noted that solenoid coil manufacturer’s state for their intrinsic safety coils that if used without a barrier a series resistor of a certain value must be used, this is to provide the proper voltage drop, and in most cases, is a 12 volt drop from the 24vdc, with only 12vdc being applied to the coil.
StoneL intrinsic safety coils requires the use of a 24vdc barrier with an end-to-end resistance of 250-305 ohms. This provides the 12vdc required by our coils.

7.) I see that you offer 2 versions of position transmitter QX/QN5_ (standard) and QX/QN7_ (high performance) with the same 4-20mA output, why do you offer both and when should I select the high performance option?
The QX5/QN5 features a potentiometer based 4-20mA position transmitter. It is sufficient for most applications where high precision is not needed and the device is not exposed to high vibration. In high vibration or high cycle applications standard potentiometers will typically function, but may have a shortened life. This is caused by the wiper wearing a groove in the resistive element. This will cause the reading to jump as it climbs over the edge of the groove.

QX7/QN7 is also potentiometer based, but utilizes a high performance, precision, MIL-spec potentiometer. It features a hardened co-molded resistance element and precision stainless steel ball bearings. This version provides precise, reliable feedback and withstands high cycle and high vibration applications.

So if you need precise feedback or have high vibration application select the high performance, otherwise the standard version should perform well in most other applications.

Netowrking FAQ’s

1.) How many devices can be placed on a Protected “T” or Protected Drop switch?
Answer: Only one device can be placed on a Protected “T” or Protected Drop switch due to the fact that the current draw of two devices would be higher than the reset current level of the Protected “T” or Protected Drop switch (less than .025 Amps).

2.) Can I operate more than one AS-i Network with one AS-i power supply?
Answer: Yes, you can operate more than one ASi Network with one ASi power supply by using power conditioners. You will need 1 power conditioner per network or segment. This is required for signal decoupling between the two networks. Standard power supply and power conditioner current limits apply.

3.) Can I use redundant power supplies in an AS-i Network?
Answer: The only method available for redundant power supplies on an AS-i Network is through the use of a Power conditioner for redundant inputs. When using this power conditioner, two supplies are wired in “hot-redundant” mode to the power conditioner terminal block. The AS-i connection is made from the output of the Power conditioner to the network to be powered.

4.) What would cause all slave devices on an AS-i Network to indicate a fault?
Answer: All slaves indicating a fault could be explained by ‘no communication’ over the ASi wire. The following cases are possible explanations for such a scenario: (1) A non ASi power supply is used to power the system (2) A non ASi device has been wired to the ASi cable (3) Faulty ASi power supply (4) Faulty ASi master or gateway.

5.) What kind of wire should I use for an Asi Network?
Answer: Many factory automation plants use the AS-i flat cable. However in the process industries, round cable is almost always used. When using round cable, it is recommended you use 2 conductor, 16AWG, non-twisted, non-shielded wire with the following electrical specifications (at 167 kHz): Capacitance 52 – 78 pF per meter, Impedance 64 – 96 Ohm per meter and Conductance 4 – 5 nS per meter. See our AS-i cable here

6.) Can you make an ASI segment intrinsically Safe?
Answer: No, there is too much capacitance inherent in the slave devices (enables communication) However, AS-i I/O modules could be located in the safe area and I.S. Sensors could be run through a barrier to the I/O Module.


Hazardous Locations FAQ’s

1.) How do I determine which IS Barrier is compatible with StoneL’s IS Solenoid.
Answer: Here is how to determine if a barrier is capable of operating our IS Solenoid. If all of the following are true, our solenoid will work with the barrier in question.

The Imin for our IS Solenoid is 50ma. Imax is 175ma.

Vmax must be greater than or equal to Voc (Vmax>= Voc)
2. Imax must be greater than or equal to Isc (Imax>= Isc)
3. Ci must be less than Ca (Ci<Ca)
4. Li must be less than La (Li<La)
Barrier must be capable of handling 50ma draw
Internal resistance of Barrier must be 250 Ohms or less.

2.) My customer has specified that equipment must be CSA approved. Many StoneL devices carry a cFM approval, does that mean that they can be used in Canada?
Yes- FM Approvals has been accredited by the Standards Council of Canada (SCC) as a testing and certification organization for electrical and electronic equipment.