Tricks of the Trade: Hard-Earned Field Lessons

Experience in cryogenics isn’t just about hours logged, it’s about exposure to the odd situations that don’t show up during training. Small details and habits, learned the hard way, can prevent equipment damage, delays, and headaches for you and the next driver.

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Dust Caps

Don’t tighten them all the way down.

These are to keep the dust, critters, and other contaminants out of the line. Generally, a thread or two is enough. If you snug down dust caps when the line is cold, the joint will expand as it warms and seize. The next driver will have to beat it or use their pipe wrench to get it off.

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Catching Prime

Opening the discharge and closing the recirculation at the same time can balance the suction and discharge pressures to help keep the pump from cavitating.

Catching and holding prime requires balancing suction and discharge by opening the discharge while closing the recirculation to prevent cavitation. Priming can be especially difficult when delivering to high-pressure tanks or when trailer levels are low. Best practice is to get the pump cold, raise trailer pressure to about 30–35 PSI, purge the delivery hose,and open the customer station. With the discharge valve closed, engage the pump, bring RPMs up carefully, then open the discharge while closing the recirculation until flow is established. Once flowing, manage leaks and set discharge pressure roughly 50–100 PSI above customer tank pressure.

If belts are screeching, rubber smells hot, or prime won’t hold on a high-pressure tank, shut down and verify whether customer venting is permitted. With low trailer levels, confirm you’re on level ground with airbags up, disengage the pump, and attempt to rebuild trailer pressure—sometimes, despite everything, priming just won’t cooperate.

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Pressure Builder Management

Pushing too much liquid through the pressure builder can cool it below its ability to flash liquid to vapor and cause trailer pressure to drop by top-fill effect.

Forcing too much liquid through the pressure builder can flood the vaporizer and drop trailer pressure. Watch snow buildup closely—heavy frost on the upper coils means heat transfer is lost. Best practice is to rely on the lower coils early in the delivery and preserve the top coils for later: cold bottom, warm top.

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Cold-Weather Fuel Prep

Buy #1 diesel and/or treat your fuel with anti-gel when the weather drops into the 30’s.

When temps drop into the 30s, switch to winterized fuel or add anti-gel, especially for the pony motor. Confirm the pony motor starts during pre-trip. If it’s sluggish or won’t start, treat the fuel or address it before heading into colder territory. Keeping it running while driving in extreme cold is legal and can save you from a no-start later.

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Nearly Empty Tanks

Sometimes top-filling and bottom-filling don’t abide by the normal parameters.

Tanks with a low supply level don’t always follow the usual top-fill and bottom-fill rules because of temperature gradients and stratification. The bottom of the tank is typically the coldest, while the upper walls can be much warmer when liquid levels are low, especially in hot weather. In summer conditions, top filling a low-level vertical tank can rapidly build pressure as liquid from the sprayer heads hits warm walls and flashes to vapor; when normal pressure control isn’t effective, bottom filling with the customer vent open may be required.

Conversely, bottom filling a nearly empty tank can drop pressure if liquid is pushed in too hard. High discharge pressure can create a liquid “geyser” that sprays into the vapor space, condensing vapor back to liquid and lowering station pressure. The solution is to reduce pump discharge pressure—without losing prime—until the flow calms down. Once enough liquid accumulates to absorb the incoming stream, tank behavior returns to normal.

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Wrap It Up

Experience is cumulative, and our line of work is full of nuance that you only learn in the field. Small habits can save you and the next driver a lot of trouble. If you have any pro-tips that others might not know, drop mean email, and I’ll put it in the next one.

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