No Steam Flowing

  1. Verify the external steam valve is opening properly.
  2. Verify the PSX heater stem is opening.
  3. Ensure that all check valves are functioning and properly oriented.
  4. Blow out the steam strainer upstream of the heater.
  5. Ensure the steam pressure exceeds the system pressure as shown in Equation 1.

Rough Operation possible causes

  1. Liquid Flow rate has quickly dropped, leading to overshoot on temperature and potential flashing in the pipe. WARNING!! IF THE LIQUID FLOWRATE DROPS MORE THAN 25% IN LESS THAN ONE MINUTE, SEVERE HAMMER CAN OCCUR.
    The fluid or slurry pump should operate with a steady, continuous flow to the PSX heater. reductions in flow rate should occur slowly. Ideally, liquid flow reductions of 10% or more should occur over several minutes to allow the temperature control loop to react properly.
  2. Heater On/Off – If the steam isolation valve is shut down before the heater is closed, fluid can back up into the steam injector and steam line. Follow heater shutdown procedures by always closing the Prosonix heater stem before closing the steam isolation valve.
  3. Steam Flow Control – Only control steam flow via the PSX Heater integral modulating actuator. Do not control steam with an external modulating steam control valve on the steam line.
  4. Excessive condensate in the steam supply. This generally occurs only at startup or if the steam trap is undersized. Purge condensate from the steam line and ensure the system is properly trapped.
  5. Water pressure is not sufficient to prevent flashing or two-phase flow at the water discharge temperature. This condition usually occurs above 212°F (100°C). It can also occur at lower temperatures if there is a vacuum in the discharge piping.
  6. Dissolved air or other gases in the liquid vaporize (or small bubbles become much larger) when heated. These bubbles implode against the walls of the discharge pipe. Ensure there are no high points in the piping where gases can collect. Install an air eliminator to remove gases from the liquid.
  7. The system pressure exceeds the allowable level listed in Equation 1.

Pl ≤ {(Pst + 14.7) x 0.7} -14.7
Equation 1 (English)

Pl ≤ {(Pst + 101) x 0.7} – 101
Equation 2 (SI)

Where:
Pl = Liquid pressure present at PSX Heater (PSIG)(KPa)
Pst = Steam pressure at PSX Heater steam inlet (PSIG)(KPa)
Note: If the process requirements exceed this limit, please contact ProSonix Customer Service.

Noise

  1. Excessive condensate in the steam supply. This generally occurs only at startup or if the steam trap is undersized. Purge condensate from the steam line and ensure the system is properly trapped.
  2. Flow rate is excessive for the heater model. Verify heater sizing.
  3. Excessive superheat is present (> 75°F, 42°C). Contact ProSonix to review.

Trouble Achieving Temperature Rise

  1. Verify steam piping is sized to meet steam flow and pressure as shown on the PSX Heater sizing worksheet.
  2. Verify current conditions and steam pressure versus the original PSX Heater sizing worksheet.
  3. See “No Steam Flowing” above.

Poor Temperature Control

  1. Heater is operating outside of the recommended range. Please verify design conditions. If necessary, a new diffuser with a different operating capacity should be installed. Contact PSX technical support
  2. Temperature probe is in a location providing poor feedback to the control loop. Relocate per O&M manual guidelines.
  3. Actuator not properly set up. Recalibrate per O&M guidelines.
  4. Actuator not fully opening or closing. Recalibrate. If necessary, an actuator positioner should be installed to provide a full operating range.
  5. The PSX Heater will respond instantly to temperature control changes, while temperature transmitters and control loops will lag in their response. The typical temperature control loop response can be 30-90 seconds. Changes to temperature or flow should allow for control response loop stabilization.

Steam Flashing After Heater Closed

The PSX Heater is a modulating steam control device and provides a class II shut-off. There will be trace steam leakage through the heater even when closed. A steam isolation valve should be installed on the incoming steam line and closed when the heater is closed, or flow has stopped.

Steam Stem Moves Slowly, Is Frozen, or Moves Erratically

  1. Air is not sufficient to stroke the actuator. (Verify that the air pressure available to the actuator is at least 5 psig in excess of the maximum bench set stamped on the actuator).
    • If a positioner is used, check that the air supply to the positioner meets the air supply requirements of the positioner.
    • If an I/P transducer is used, make sure that the pressure to the I/P is above the necessary actuator pressure.
  2. The control signal is missing or erratic?
    • In direct pneumatic control, the airline may have an erratic output due to water, oil, plumbing tape, or other matter in the air pipe.
    • In an electronic control system, the control signal may be erratic or missing.
      • Is there electronic interference or ground loop issues?
      • Is the controller outputting a consistent signal?
  3. Is the stem packing interfering with the stem movement? a. Is the packing too tight? Please follow packing tightening procedures from the manufacturer or in this manual.
    • Is there buildup on the PSX steam stem? Clean or replace the stem.
  4. Has foreign material gotten into the heater stem housing or the gap between the stem plug and steam jet diffuser?
    • Are steam strainers installed per the instructions in this manual?
    • Has there recently been work done on the system piping that may have introduced material (weld slag, construction debris, etc.) into the heater?
    • Has there been a system “backup” that may have forced particulates or other material into the steam chamber?
    • Is the steam system prone to buildup on other steam components? If so, boiler feedwater treatment may need to be adjusted.

Note: Please refer to your Heater O&M Manual before operation or servicing. Never pressurize the PSX Heater if the actuator is not fully assembled and connected to the steam stem. Use proper lockout procedures. To receive a free copy of your PSX Heater O&M Manual, please contact us at 800-849-1130 or info@psxllc.com.

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