In this industry we have to keep all our production equipment clean and not just because
we're clean sanitary people - I mean clean down to the microscopic level. The presence of microbes is
a major risk to our products and ultimately our customers' safety. We use pressurized moist heat
saturated steam to kill microbes. Small items can be sterilized in an autoclave like this one,
but for large items or fixed equipment we use steam-in-place systems where saturated
steam is piped directly into the equipment. But wait - this isn't a video about sterilization.
Steam's unique physical properties present some real and potentially devastating challenges
and that's what we want to look at today. Always make sure to wear your PPE - lab coat, gloves and
safety glasses. When water boils it turns into steam. Steam has a much larger volume than water.
So one liter of water can produce sixteen hundred liters of steam. That expansion generates a lot
of pressure. The reverse is also true . If you have a system pressurized with sixteen hundred
liters of steam and suddenly the temperature drops - well what happens to the steam?
It condenses back into water and that's called a steam collapse. Sixteen hundred liters becomes one
liter creating a vacuum. I think this principle will be a lot clearer after we smash some stuff.
Want to try it? Let's go to the lab. Add about 500 milliliters of water to a 1 000 milliliter
pyrex beaker. Place a stir bar in the beaker and set it on the hot plate. Turn up the hot
plate temperature control until the water comes to a rolling boil.While we're waiting,
fill a bucket about one third of the way with ice, and add enough water to completely cover the ice.
Transfer 100 milliliters of boiling water into an empty plastic soda bottle, cap it,
and submerge the bottle in the ice bath. Let's see that again. The bottle collapses on itself.
Okay, so you're not impressed . Let's try the experiment again. This time with an empty
aluminum soda can. Transfer 10 to 20 milliliters of boiling water to the can, and place the can on
the hot plate until you see steam rising from the opening. We can't cap an open soda can,
so instead, in one fast motion, turn the can over and submerge it into the ice bath.
Soda pop! Let's have an instant replay.
So why did the bottle and the can collapse? Remember that gases like steam take up more
space than liquid. The container fills with the steam and pushes out the air.
The ice bath cools the steam very quickly, and it collapses back into water. The water takes up
less space than steam creating a vacuum. Now the air pressure outside the container is much higher
than the inside with almost 700 pounds of force pushing on the bottle and the can - and of course
they both collapse. Vacuum smashing bottles and cans is fun and takes up less space in your
recycling, but why is this experiment important? As i said when we started, we use steam all the
time in biomanufacturing. You'll be operating and maintaining production equipment like mixing
tanks and fermenters and using steam-in-place systems. These vessels have to be properly vented
and sterilized according to the SOP because they have the same potential to collapse.
It's hard to believe but a 5,000 liter bioreactor can collapse just like an aluminum can.
Thanks for watching.