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Sampling systems handbook and approval guide
6. Sampling systems: installation and use
6.1 Location and installation
The location selected for a proposed sampling system must meet the requirements of the CGC. Any nearby equipment must not adversely affect the operation of the sampler or delay its operation in any manner. Lighting in the area of the sampler must be sufficiently intense (approximately 100 lux) and preferably permanently installed in order to allow visual inspections of the sampler.
6.2 Segregation of samples
This section describes how to locate samplers and segregate samples in such a way as to ensure that the sample is representative of the grain lot.
- On inward (receiving) sampling systems, the sampler must be located before or immediately after the initial elevation. The sample is considered representative only after the entire lot of grain being sampled has passed the sampler.
- On outward (shipping) sampling systems, the sampler must be located after the final elevation and as close as practical to the end of the loading spout. The sample is considered representative only after the entire lot of grain being sampled has passed the sampler.
- Samplers located in spouts must not come after a vertical drop of more than 15 metres or be within 0.6 metre of any bends in the spouting.
- Before beginning a shipment to railcars, the grain delivery system must be purged with the grain to be officially sampled. The purge must be to the furthest return-to-house point in the shipping system. The grain delivery system must also be purged in the same way if the elevator operator changes the grade or grain to be sampled.
- Outward samplers used for loading railcars must be installed or operate in such a way that the railcar into which the sampled grain is loaded can be identified for each sample.
- Where the sampler is located above the weighing system, or below the scale but before shipping or pre-weigh bins, there must be automated means available for CGC staff, such as bin or hopper empty sensors, to identify that the grain being sampled has been delivered to the carrier.
6.3 Divider installation
The divider associated with a sampler must be installed in accordance with the manufacturer's specifications and be reasonably close to the main sampler. The divider installation site must be free of hazards, have adequate space for inspecting the device, and be sufficiently clean from dust, spilled grain, and refuse. Lighting in the area of the divider must be sufficiently intense (approximately 100 lux) and preferably permanently installed. Dividers may be of the swing arm type or the rotary type (see Figure 6.1).
Figure 6.1 Swing arm divider and rotary divider
The black-and-white line drawing is showing a swing arm divider and a rotary divider. In both diagrams the path of the sample and the path of the surplus sample are shown.
6.4 Timer installation and use
Sampler timers may be either analog or digital, and must have a maximum 1-second dial or timer interval setting. A sampler timer must be accurate to within ±1 second of the cycle time.
At facilities where the timers reside in the programmable logic controller of the facility, access to the programming must be made available on request. The facility must bring any adjustment to the timing of the sampler to the attention of the CGC inspector on site.
When loading or unloading railcars or trucks, the timer of a cross-stream sampler used for official samples must be set to an interval not greater than 20 seconds. The divider reduction rate and the sampler timer interval must be set to collect a sample quantity representing between 0.0025 percent and 0.0075 percent of the lot being sampled.
When loading or unloading vessels or barges, the timer of a cross-stream sampler must be set to an interval not greater than 45 seconds. The divider reduction rate and the sampler timer interval must be set to collect a sample quantity representing between 0.0005 percent and 0.001 percent of the lot being sampled.
When loading railcars where the sampler is below the weighing system, it is permitted to interlock the sampler with a scale draft counter if the following is met:
- Where the draft of the bulkweighing system is less than 8 tonnes, the sampler may be timed to traverse at approximately the middle of the draft discharge or it may traverse at a random interval during the discharge.
- The random interval must not be controlled by an operator and must ensure that the sampler traverses during the period when grain is flowing.
It is also acceptable to have the sampler traverse the grain stream based on the time during which grain is actually flowing past the sampler in a spout. To accomplish this, a flow detector is installed immediately before or after the sampler and is integrated with the sampler control. The flow sensor activates the sample interval timer when product is flowing in the spout and stops the time when there is no flow. When flow is detected again, the interval timer resumes from the point where it stopped.
For example, if the sample interval is 20 seconds and flow stops when the elapsed time since the sampler last traversed is 16 seconds, the sampler traverses when flow has resumed for 4 seconds.
6.5 Blending limitations
Subject to the limitations of the Canada Grain Act and the Canada Grain Regulations, the blending of grain must be completed in an even and uniform manner before the grain reaches the sampler.
6.6 Integrity of grain lots
Means must be provided to prevent the addition of grain or other commodities to the grain stream, or the removal of any portion of the sampled grain, after it has passed the sampler. Feeder spouts or diversion spouts after the sampler must be sealable with CGC security seals, keyed locks, or positive electronic means under the direction of the CGC. If, during official CGC inspections, security means are found to be missing or to have been tampered with, the shipment or lot will be rendered non-representative.
The sampling, weighing, and delivery systems must not be manipulated, operated, or circumvented in any manner intended to purposefully influence, degrade, or bias the sample, any part of the sample, or the lot of grain the sample represents.
