Welcome to FAQs

We call static pressure the highest pressure applied in any of the sides of a pressure sensor.

Notice that, the differential pressure could be zero. This implies that the pressure in the low and high side of the pressure sensor are the same. However, this does not means that the static pressure is withing the limits of the transmitter sensor specification.

Consequently, the pressure in any of the sides cannot surpass the limit of the static pressure value assigned by the sensor manufacturer.

SMAR offers different grades of material for its explosion proof and intrinsically safe field products.

To choose the product housing material you need to specify one of the following options in the order code.

H0 – Aluminum (IP/TYPE)

The most common for many applications where corrosion is not a serious issue. It has the advantage to be light and SMAR offers many protecting painting options (Polyester, Epoxy) to increase protection.

H1 – 316 Stainless Steel (IP/TYPE)

An excellent option considering it has a high resistance to corrosion, but it has the weight as a disadvantage. About 3 times heavier than Aluminum. SMAR also offer this option with extra protecting paint (Gray Munsell N 6.5 Polyester – P0), that improves its application for corrosion and saline environments.

H2 – Aluminum for saline atmosphere (IPW/TYPE X)

This is a grade of Aluminum Alloy is improved for high saline environment and can also be painted (Polyester, Epoxy).

H3 – 316 Stainless Steel for saline atmosphere (IPW/TYPE X)

This is a grade of stainless steel is improved for high saline environment. The material is tested for 200 hours according to NBR 8094 / ASTM B 117 standard. It is the most expensive option.

H4 – Aluminum very low copper

Used for high corrosion resistance with the advantage of the light weight of the Aluminum. However, it does not offer the same corrosion resistance of the stainless steel that is approximate six times better.

Consulting with our Customer Support you can discuss the possibilities to expedite an order partially or completely.

Every case needs individual treatment, and the possibilities are always linked to other conditions.  Conditions such as inventory and production availability.

Please consult Customer Services at: 713-849-2021 (ask for sales) or email to: sales@smar.com.

Smar International has a repair, calibration and improvement department.

If you need to send a product to us we recommend trying to solve the issue by yourself by reading the product manual.  You also have the alternative to call us for guidance.

In case that you really need to send the product for our evaluation call or send us an email explaining the basic problem(s) that you are having.

Please consult at: 713-849-2021 (ask for sales) or email to: sales@smar.com.

For more information go to: RMA and ECC page

Orders can be treated as regular or as a rush order. A rush order may include extra fees.

Pressure Transmitters and some of other available devices have a large variety of options.  You can understand this by looking at the number of options present on a full order code.

This implies that in some cases, the devices need to be assembled and calibrated according to the order.

This level of customization is the main reason that it is just impossible to have all combinations of transmitters or other devices ready to go on the self.

The best way is to consult SMAR International, to correctly specify the product options and determined the desired quantities.

With this information on hands and knowing your timing we will be glad to have you informed of our best delivery time, prices, and purchase terms.

Please consult at: 713-849-2021 (ask for sales) or email to: sales@smar.com.

Yes, rush order is a strong part of our operations.

We take rush orders seriously.  We give high priority for your plant emergency situations and we will let you know what can we do as soon as possible.

Please contact us with further information on your rush order via phone (713-849-2021) or by email (sales@smar.com).

Everything is about inventory and how busy is the production department at the time.

We will work in the best way we can to reach your delivery time and product specifications. Or we will let you know about other possibilities.

It is possible to Zero and Span (re-ranging) and adjust variable on the LD301 without having a HART communicator.  This is accomplished through 2 holes in top of the transmitters, right below the certification plate, and using the Smar Magnetic Screw Driver.

Before doing any change, it is necessary to make sure the transmitter have 2 internal jumpers set to the right position. These jumpers are verified before the installation on the field to avoid any hazard.  If the transmitter is already installed and you are in a classified area, take the transmitter to a safe are to make the jumper configuration.

Once the transmitter is in a safe area, remove the cover that protect the electronics and locate the jumpers in the top part of the electronic board.

Each jumper base counts with 3 golden posts or 3 aligned holes (this will depend of the transmitter version).

The jumper itself is a 2-pin short and can be place in the 2 pins on the right or the 2 pins in the left.

See below the possible combinations and their effect:

Here is a summarized explanation for each of the above combination:

You can find this information and more details on the LD301 Manual on section 4.

The straight answer is yes, however it depends what kind of results you are expecting.

For instance, when you connect a second sensor on a TT301 HART Temperature Transmitter is to get the differential value between both sensors and NOT each individual temperature value.  Other results in using two sensors are: Using the second sensor as a Backup, or getting the Maximum, Minimum, or Average value between them.

The TT301 HART® Temperature Transmitter can only show one value from the possibilities presented above.

On the other way, the Smar TT302 (FOUNDATION Fieldbus)  and the TT303 (PROFIBUS PA) can indicate individual values coming from 2 connected sensors plus all the possibilities shown for the TT301 HART version.

For more details on connecting sensors to a TT301, click here to see the blog.

For more details on connecting sensors to a TT302 ot TT303, click here to see the blog.

First we need to divide the answers for the line of HART transmitters and other for the FOUNDATION and PROFIBUS PA transmitters.

HART transmitters

This is a classic graphic to understand the Power Supply minimum output value related to the total load of the line.

We can see above that if the load is 250 Ohm then the minimum voltage for the Power Supply is 17 Volt. The maximum will always be 45 Volt.

Of course if the load of the line increases the minimum voltage for the Power Supply will also increase. We should always use a voltage value above the minimum value.  Most typically 24 V and 32 V power supplies are very popular.

FOUNDATION and PROFIBUS PA transmitters

The load for these lines are typically the resistance added by the network cable itself.  That, consequently, makes the added load relatively small.  Best way is to have in mind that it is expected to see a voltage between 9 – 32 VDC at the SMAR FOUNDATION and SMAR PROFIBUS PA transmitter terminals.

Same thing here, a power supply that can hold voltage around the 24 V will make a good choice.

It is also good to know that SMAR FOUNDATION and PROFIBUS transmitters have a quiescent current consumption of 12 mA.

For these 2 protocols, noise and ripple should fall within the following limits:

a) 16 mV peak to peak from 7.8 to 39 KHz.
b) 2 V peak to peak from 47 to 63 Hz for non-intrinsic safety applications and 0.2 V for intrinsic
safety applications.
c) 1.6 V peak to peak from 3.9 MHz to 125 MHz.

SMAR Temperature Transmitter can use a variety of RTDs, TCs or sensor that provides resistance or mV as an indicator for the measured variable.

This is the reason that this SMAR transmitter is also called a Universal Transmitter.

See below a list of supported RTDs, Thermocouples, Ohm ranges and mV ranges.

Downloads:

TT300 Catalog

Input List Only

SMAR Temperature Transmitters can operate with one or two temperature probes.

The transmitter can be set to different interpretations when two temperature probes are connected.

It can read the differential temperature of two points or get the minimum, maximum, or average temperature. The transmitter can switch automatically to ready from the other probe in case that one of them opens or get shorted.  Due to this reading switching, this mode is called “Backup”.

When two probes are connected they must be identical.

An individual RTD can be connected in a 2, 3 or 4 wire configuration, however they can only be connected in a 2 wire configuration if two RTDs are used.

Other option is to use two Thermocouples (TCs). Just as a reminder, TCs are always connected using two wires.

All HART SMAR transmitter have 2 extra connectors for testing the loop current.

Open the Terminal Block Lid of the transmitter and look below the contacts that connect to the power supply. Find the word “TEST” between two small terminals.

Set your multi-meter in current measuring mode and connect it on those terminals.  Watch for the polarity.

When you place the current meter on those two connectors, the current will continue to pass through your loop and transmitter, but it will also be deviated to your meter for verification.

Important Note: Make sure that your process is safe and halted in a way that during testing or maintenance activities it will not cause any type of damages.

Refer to this picture from the Manual:

SMAR manufactures pressure transmitters since 1980. The initial version used the strain gauge technology for the pressure sensor and the device was completely analog.

In the early of 1984, SMAR changed the sensor technology to use a capacitance as a way to measure pressure. In this way, pressure is measured by the change of the capacitances in a double capacitor sensor.  The final result is that we can determine the differential pressure applied.

Initially the transmitter was analog providing straight 4-20 mA output proportional to the applied differential pressure. However, around 2 years later SMAR created their own digital protocol.  SMAR was determine to give the transmitter the capability of remote configuration.  The new transmitter was able to provide the legendary 4-20 mA and get connected in a network to interact with a DCS (distributed control system) or to a hand-held device for operation and configuration.

To make the line of transmitters more universal/compatible with others DCS, SMAR implemented the HART protocol. In 1989.  Consequently, SMAR was the second company in the world to have a Pressure Transmitter working with HART protocol and be completely configurable with a small hand-held device.

The straight answer is yes, but there are points to consider.

It is always better to have your product repaired or updated by a trained technician. Contact Smar International, get an RMA form filled up then send it to have our people guiding and answering your questions.

Repairs done by Smar International comes always with warranty, that may differ from different services performed.

If you want to do the repair, you can order the part(s) directly from Smar International.  Before you call our sales department, make sure you know the model name and the device serial number.  In this way, we can give you the part code for the repair or upgrade you intend to do.

To email sales with your questions or other requests, please use:  SALES@SMAR.COM

Yes, all our Transmitters (DP, Pressure, Temperature, Density, Position…) have an internal FLASH memory to keep important information.

For instance, data related with the configuration and calibration will not be lost in case of a power glitch or if it goes completely off.

Not only that, imagine that your transmitter is doing Volume Totalization or PID control.  After a power failure the last value for the totalized volume and last output calculated by the PID controller will be available.

There is an extra protection for configuration and calibration data on the SMAR LD300 and LD290 series of pressure transmitter.  Those transmitter can send data to an extra Flash memory located in the pressure sensor. Obviously, in case of a malfunction, like lost of calibration or configuration data, these data can be retrieved.

Yes, you can extend the regular warranty in units of one year to the maximum of 10 years.

Please consult or sales at 713-849-2021 or sales@smar.com

Let’s talk over one example for the sensor label reading.

When you get a Range 4 pressure transmitter, you know that according to the catalog this device is specified to work from -14.5 to 360 psi.    However, when I look at the transmitter sensor label you could see two different notations.

1) If the transmitter is relatively new you will see the same thing: -14.5 to 360 psi. Great no confusion! This is the working range for this pressure transmitter.

2) In the other way, you can see: 0.625 to 25 bar.  This is an old notation for the sensor label.

If you convert from bar to psi you will see that this will be around 9 psi to 360 psi. Still, that looks wrong!! How about the negative pressure!!!

This notation is not about the working range of the transmitter, instead it shows the smallest possible working span (9 psi) and the maximum working pressure (360 psi).

So, you can relax, this is the same range that you have purchased, just with other interpretation.

A few things.

Is this a Gauge/Absolute, or a Differential transmitter?

Does the transmitter require a drain/vent plug?

Get the drain positioned down (Drain) for gas applications and the drain positioned to up (Vent) for liquid process applications.

Important that the Drain/Vent material matches diaphragm material once both parts are relatively low mass and could be more affected buy the corrosion.

How corrosive is the process? You may need to use Hastelloy-C or Monel for the flange, instead of the regular 316SST.

The LD300 series is assembled in an Explosion proof and Weather proof housing and has
Intrinsically safe certifications.

Housing in made of injected aluminum with polyester painting, epoxy painting or 316 SST – CF8M (ASTM – A351) painted or not.

Housing Complies with NEMA 4X/6P, IP66 ou IP66W*, IP68 ou IP68W*.
Note: The IP66/68W sealing test (immersion) was performed at 1 bar

See next table;

Let me start by saying that a HART transmitter can also provide the 4-20 mA as an old good analog transmitter.

A HART transmitter can directly replace a legacy analog transmitter that you already have installed in the plant.

You can literally remove your analog transmitter from the line and have it replace with a HART transmitter using the same twisted cable.  Yes, it is compatible with your power supply and the twisted pair wiring used before.

There are many advantages that a HART transmitter can bring to your plant.  See some of the presented benefits below and you will be able to understand immediate advantages for your operations.

Some immediate benefits are:

1. We can use remote configuration using a HART interface to communicate with the transmitter.
2. Now users have a digital access to the signal and other internal parameters.
3. Considering that they are microprocessor-based, they can make internal calculations as PID control, Square Root, Totalization…
4. Better and easier for diagnostic and routine maintenance.
5. Your maintenance personal will feel comfortable to deal with a 4-20mA loop.
6. Manufacturers add troubleshooting information.
7. Better integration with a DCS (Distributed Control System)

I don’t know about you, but I can definitely see that they are a better asset to the plant.

SMAR carries many devices with built-in PIDs and other control algorithms. These controllers are present in dedicated controllers, transmitters, PLCs, and in or modern DCS (Distributed Control System), the System-302.

However, I believe that your question is in reference to PID controller units for panel installation, with its own display and buttons interface to interact directly with the user.

For this case I should recommend you to look at the CD600Plus.

The CD600Plus is a stand-alone multi-loop controller that can resolve up to 8 PID controls.  It is block configured using an easy to learn Windows graphical interface.

See more on the CD600Plus

Even if you know that the load added by the devices in the loop totalizes more than 250 Ohm (that is the smallest load needed to communicate HART). It is NOT recommended to drop the classic 250 Ohm resistor from the current loop.

Consider this.

Let’s say you are going to do maintenance on one device in the loop.  When you remove this device from the loop and take it to the workshop. Let assume that you shorted the 2 points where this device was installed, so the loop keeps closed.  In this situation, the total load now could get lower than 250 Ohm based on what was left on the loop.   If this happens, the HART communication in the line is compromise and may not work anymore.

On the other way, put in mind that too much load in the line may need a higher voltage power supply for the loop.

They are high quality industrial transmitters packed with great features. Since the start of the design we have always placed our attention to durability and availability in an industrial environment.

Years of experience in the business have positioned our products among the best and more creative products available.