The Monitor

Production Process Insights

Time Stamp Your Samples for Effective Process Correlation

Posted by Kevin Kirst on 8/3/16 7:30 AM
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Time stamping samples can help run a safe, efficient operation at chemical plants

Running a safe, efficient operation requires analysis of controlled, real-time data obtained through representative sampling within a process. Nowhere is obtaining that data more critical than within a refinery, chemical or petrochemical plant. 

 Sampling in for these industrial applications must be repeatable and reliable, every time. Within these environments, samples are needed to:

  • Verify and validate product constituents to ensure they meet quality specifications
  • Monitor process efficiency
  • Troubleshoot sources of product contamination
  • Ensure operator and environmental safety


Some refineries and plants require even more. Recently, two refinery customers, one on the Gulf Coast and one in the Midwest, requested a new method of validation for their representative sampling program – time stamp verification.

Sample time stamp verification allows for data correlation

Time stamp verification provides a time-specific signal to plant or process operations when a sample is taken. This signal conveys an important piece of information – the exact time of sampling – allowing operators and lab analysts to closely correlate a physical sample with the plant’s operational parameters in real time. They can match analysis of the sampled product with the specific processing time to confirm online instrumentation or compare data with lab measurements.

As plant operating parameters can change slightly, it is important for management to know whether the change is a normal variation, a process deviation or an on-line instrumentation or analyzer issue that must be adjusted. And, plant management cannot know if there is an issue without correlation of the time of sample.

Additionally, the time stamp feature can help ensure a sample point is not overlooked when an operator collects manual samples, as the time stamp confirms that an action has taken place as scheduled according to sample protocols.

How sample time stamp verification works

How the sample time stamp verification works: A small switch is designed and installed on the sampler valve handle. When a sample is manually obtained, the movement of the valve handle by the operator triggers a small single-point dry contact input switch enclosed within an explosion-proof housing for safety. When the contact actuates, it sends a signal to the plant or process control system to provide a time stamp for the operation of the sample valve.

Why sample manually, anyway?

In many other industries, sampling can be automated within a process so a composite sample can be obtained without operator involvement. However, in volatile and hazardous process environments, automatic sampling comes with added cost (equipment and special installation) to address safety risks. The usefulness of pneumatics – or samplers operating via air actuation – can be limited in those environments as well. Pneumatic operation also offers risk to a lesser degree, as some type of electrical interface is needed to automate sample collection.

In the manual sampling environment of a refinery or chemical plant, the new time stamp feature adds much of the value of automated sampling – that is, the ability to correlate the time the action of sampling occurred to the specific process conditions at that time – without the added risk.   

The time stamp feature is available on Sentry® low-emission manual sampling products with sample valves, including the Sentry MBP, Sentry MFV, Sentry MVD and Sentry MVS samplers for chemical and petrochemical and oil and gas markets.

The time stamp feature is only one way that Sentry products help a wide range of global companies to monitor sample timing. Our sampler controllers automate sample timing and quantity for many liquid, slurry, solid and powder materials within a process and can be customized for a wide variety of applications. 

Sentry's Industrial Representative Sampling eBook

Topics: Hydrocarbon Processing, Upstream & Midstream

Written by Kevin Kirst

As industry manager for the refinery market, Kevin employs his 25-plus years of experience in engineering, application support and sales to develop new ways to sample, monitor and measure customers’ processes, with a primary focus on the crude oil refining industry. Like all our company employee-owners, Kevin is committed to developing technologies and equipment that allow customers to operate their processes at optimal efficiency while maintaining high levels of safety and product quality.

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