What are Outage Tubes and Why are they Important?
There are many factors to consider for liquid sampling. That's why we put together a five-part Ask Swagelok video series that discusses the importance of maintaining proper vapor space compression, the role of outage tubes, how vapor space is affected by sampling system design, and what you need to know to minimize the risk of cylinder rupture.
In this first video, fluid sampling expert Matt Dixon explains what outage tubes are and why they're important in liquid sampling.
Video Transcript
LUCAS TREU:
Hi there. I'm Lucas Treu, and this is Ask Swagelok. I'm here at the Solon Tech Center today with Matt Dixon, one of our fluid sampling experts, and we're talking about gathering liquid samples—specifically into metal cylinders. So Matt, when we look at metal cylinders, can you tell me a little bit about them? What are outage tubes, and what role do they play?
MATT DIXON:
Sure. An outage tube is designed to keep a certain amount of gas—called a vapor space—inside the cylinder. That vapor space is really important when you're sampling a liquid inside a sample cylinder.
Liquids tend to have a higher rate of thermal expansion than the metal cylinder containing them. So if you capture a liquid sample in a cylinder and the temperature increases, without that vapor space the liquid would try to expand with nowhere to go. That can create immense hydraulic pressure and potentially rupture the cylinder.
By having that vapor space, you provide a place for that incompressible liquid to expand into. You’ll still see some pressure increase because the vapor is being compressed, but you won’t get that extreme hydraulic pressure, and you won’t rupture the cylinder.
LUCAS TREU:
All right, great. Well, thanks for that. And thank you all for joining us for Ask Swagelok.
