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Production Process Insights

Solutions to Your Most Common LPG Sampler Problems

Posted by Randy Cruse on 4/13/20 8:00 AM


LPG sampling systems help you safely and effectively sample liquefied petroleum gas (LPG) and other gases with high vapor pressures. But even the most reliable LPG sampling solution will need ongoing maintenance and service. When your LPG samplers aren’t working properly, these troubleshooting tips can keep your system running smoothly.

A standard liquefied petroleum gas system has one process inlet, one process outlet and one vapor recovery/flare outlet. It can often be modified to include a sample cooler if it’s used in high-temperature service, and can also include a sight flow indicator to verify flow and level. Regardless of standard or modified, an LPG system takes regular operation and maintenance. 

Operating your lpg sampler 

Prior to utilizing your system, following these general operational tips will provide you with clear indication points to identify potential issues.

  • Ensure process supply and return block valves are open allowing process to flow through the system
  • Install the sample cylinder using quick connects (if outage tube is installed on a cylinder, it should be at the top) and open cylinder valves
  • Move sample valve from bypass/equalize to sample
  • Allow flow through cylinder (if system has no return, the vent valve must be slowly opened to allow flow)
  • Close vent valve, if opened for flow
  • Move sample valve from sample to bypass/equalize and close cylinder valves
  • Open vent/purge valve to allow system depressurization
  • Close vent/purge valve once pressure holds at 0
  • Remove cylinder from the system

Troubleshooting Your LPG Sampling System

Problem Solution
There's no sample/ The cylinder is empty 
  • Ensure all process valves and vent block valve are open for sampling.
  • Ensure cylinder valves are open to allow sample flow.
  • Ensure that sample pressure is detected.
  • Ensure cylinder valves are closed prior to opening the vent valve for final system depressure.
The system doesn't depressurize 
  • Ensure vent valve is open and sample valve is in bypass, equalize or off.
  • If the vent doesn’t flow excess pressure out of the system, block and bleed the system and inspect the vent circuit for valve alignment and blockages.
  • If the system depressurizes through the vent but pressurizes once the vent is closed with the system in bypass, replace the sample valve after energy has been removed.
    • NOTE:  Allow extra time for system to depressure with LPG fluid.
There's no outage (if required)
  • If an outage is required and there’s not one present, inspect the flow of the system and valve orientation. The flow should enter bottom of cylinder and exit top.
  • Ensure the cylinder is placed in the system correctly and all cylinder components are in working order. The outage tube should be at top of cylinder.


Maintain your investment with routine maintenance 

As with all sampling equipment, maintaining maximum uptime and efficient sampling processes requires routine maintenance inspection. It is recommended to follow these steps to ensure continued reliability.

  • Inspect full system visually for defects or leaks.
  • Inspect gauges and sight flow indicator for clarity and functions.
  • Verify valve orientations are proper for taking a sample.
  • Take sample.
  • Note any issues in the process.
  • Verify vent valve and check valve function and orientation.
  • Verify quick connect function on each visit. Change quick connect annually or as needed.
  • Verify Flex hose integrity and change flex hose every two years or as needed.

Low Emission sampling helps you capture representative samples simply, safely and accurately. Contact us at +1-262-567-7256 or complete our online contact form to discuss how Sentry sampling systems can help you achieve safe, simple and accurate sampling results.

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Topics: Downstream, Upstream & Midstream, Liquid & Slurry, Gas

Written by Randy Cruse

Picture of Randy Cruse
As Senior Service Manager, Randy dedicates his lengthy career to developing and delivering service programs designed specifically for refineries and their sampling programs. He understands the risks and safety requirements that come along with being a service provider in the Oil & Gas industry and brings that expertise to each and every call.