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Customizable Pulse Output Modules for Flow Rate Sensors: A Guide for System Integrators

Quick Answer: Silver Automation Instruments supplies flow rate sensors with customizable pulse output modules for system integrators. You can set pulse width, frequency range, output type, and scaling factor before shipment. This reduces field wiring errors and PLC input mismatch on skids, dosing lines, and utility meters.

Why System Integrators Ask for Custom Pulse Outputs

Most PLC and DCS cards accept a limited range of pulse input. A standard flow meter pulse signal may be 5 V square wave, 24 V open collector, or a brief reed switch pulse. If the pulse width is too short or the frequency is too high, the input card misses counts. In practice, system integrators in Malaysia, Vietnam, and Chile often ask us to change the pulse width before delivery. This avoids adding a signal conditioner in the panel.

Silver Automation Instruments treats pulse output as a configurable module, not an afterthought. The same flow sensor platform can accept NPN, PNP, open collector, or 5 V TTL output. You specify the pulse width from 0.1 ms to 500 ms. You specify the scaling factor, such as one pulse per 0.1 liter, one pulse per liter, or one pulse per kg. We program the module and test it on a frequency counter before packing.

Customization Options That Reduce Commissioning Time

We have seen projects where a water treatment skid in the Philippines needed 100 pulses per liter for a flow computer. A fuel oil system in Nigeria needed one pulse per 0.5 liter to match an existing totalizer. A chemical dosing line in Indonesia needed a pulse width below 0.5 ms because the PLC scan time was short. These requests are standard for us.

Options include pulse width changes, frequency division, push pull output, and two separate pulse channels. One channel can go to a PLC counter. The second channel can go to a local display. You can also request galvanic isolation to protect the PLC input from ground loops. We have supplied this on seawater desalination skids in Saudi Arabia and on dairy clean in place systems in Australia. For oil and gas skids in the Middle East, we can supply pulse output modules rated for ATEX Zone 1. The flow meter housing and the pulse output wiring are certified together. This avoids a separate safety barrier in many panel designs.

Flow Meter Types and Typical Pulse Settings

For water and wastewater, a Silver Instruments electromagnetic flow meter from DN15 to DN300 works well. Set the pulse output to 100 pulses per liter or 1 pulse per m3. If the water conductivity is above 5 µS/cm, the meter reads stable. Use 24 V DC open collector if the PLC input is a sourcing type. Use 5 V TTL for compact controllers.

For diesel, fuel oil, and edible oil, an oval gear flow meter with pulse output is common. These meters output a raw pulse train from a reed switch or Hall sensor. A programmable divider can convert the raw signal to a clean square wave. For a 0.5 inch line, typical output is 10 pulses per liter. For a DN25 line, output is 1 pulse per liter. Silver Instruments applies the divider and tests the pulse signal with a 30 minute run at 50 percent of full scale flow.

For gas and compressed air, a thermal mass flow meter or vortex flow meter with pulse output is an option. The converter can accept a PT100 temperature input to normalize the flow rate. Set the pulse scaling in kg or Nm3. For a DN50 vortex meter on compressed air, a pulse per 0.1 Nm3 is common. The pulse output module accepts a 24 V DC supply and drives a 10 mA load. This works for most PLC high speed counter cards.

For high accuracy mass flow, a Coriolis mass flow meter can output both 4-20 mA HART and pulse. The pulse output can be configured in kg per pulse. For a DN15 Coriolis meter on chemical injection, where viscosity is below 200 cP at 25 °C, on