The Monitor

Production Process Insights

Downstream Sampling: Match Your Equipment to the Application

Posted by Randy Cruse on 6/29/20 8:00 AM


Capturing representative samples and protecting the operator is critical in high-temperature and high-pressure applications commonly found in hydrocarbon processing. That’s why it’s essential to match your application to the sampling equipment. Here’s your guide to ensuring you choose the right sampler for your application.

Matching sampling equipment to the application

Low Vapor Pressure Liquids

A Bottle Manual Liquid Sample System is the best way to sample low vapor pressure liquids. These systems catch samples with a manual system using a simple fast loop valve.

The standard system has one inlet, one outlet and one vent line, and it can be modified to include a sample cooler or an N2 purge. This system offers a flowthrough pass, as well as a small secondary valve that allows for regulation of the flow upon collection. Samples can be collected in any type of bottle, although they typically range from 4 ounces to 32 ounces.


High Pressure Liquids

A Fixed Volume Sample System is ideal for sampling liquids under high process pressure. This type of system adds a volume chamber component to a manual system to capture samples in an intermediate stage that separates the human operator from the actual process pressure.

When the main primary valve is open, it fills the chamber with the sample. Once it is full, the operator closes the primary valve and opens the secondary valve. Then, nitrogen is introduced to sweep the fluid through that chamber into the bottle. This also sweeps the needle clean so it's process-free for each source.

The standard system has one process inlet, one process outlet, one vent line and an N2 purge, and it can be modified to include a sample cooler. If process valves are open, the system has constant flow (fast loop).


Sampling Other Liquids

MIL/MVD Bottle Samplers are the right choice for sampling liquids in a hydrocarbon process.

A manual low emission sampler samples liquids in-line without exposure to the operator. The sampler's unique features include a close-coupled ball valve specifically designed to provide low dead volume in the sample flow area, ensuring representative samples from flowing process lines at pressures up to 2200 psig (150 barg). Additionally, the pressure drop of the flowing fluid through the sampler is low, and no valve stems or other components pass through the sampling stream.


High-Temperature and High-Viscosity (HTHV) Applications

For high-viscosity materials, such as heavy oils and resids common in refineries, high-temperature, high-viscosity (HTHV) samplers are the right choice.

HTHV samplers have a robust design for fluids that are difficult to pass through a normal valve. The valve design has larger orifices, a bigger stem and bigger seat, with special material to handle the extreme temperatures built in a stainless-steel enclosure.


Liquefied Gas or High Vapor Pressure Liquids

An LPG Liquid and Gas Sample System is ideal for sampling gas or high vapor pressure liquids.
A standard system has one process inlet, one process outlet and one vapor recovery/flare outlet. It can be modified to include a sample cooler if it’s used in high-temperature service, and it can include a sight flow indicator to easily verify flow and level.

Sentry Equipment offers these systems in a four-way design with a bypass, or in a vent-to-flare design that fills the cylinder with a representative sample from the line. When sampling gas, the flow goes top down. When sampling LPG, the flow goes bottom up.


Sampling Crude Oil, Condensates and Oil and Water Mixtures 

Automatic samplers help optimize sampling accuracy and repeatability for hydrocarbon liquids such as crude oil, condensates and oil and water mixtures. They isolate the process without interrupting the process line, and offer a variety of different types depending on the application.

These samplers use air to take the sample. You can use the manual option, where you push a button to take a sample, or you can have a control system that's fully automated. These samplers handle line pressures up to 300 psi. Sample particles can be up to 3/8 inches, or 9 millimetres.


Regardless of application, capturing representative samples protect operators, maintain environmental integrity and maximize your petrochemical plant’s uptime.

Ensure you are matching your applications with the correct sampling equipment. Sentry Equipment has a wide variety of systems that can sample throughout the course of your refining process. Learn more about these systems and proper sampling processes with our webinar: Five Considerations for Downstream Sampling.

Access the Webinar

Topics: Downstream, 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.