A2 Chapter 5 Steam Traps, Water Hammer, Insulation

LIQUID EXPANSION: Describe method of operation, two pros, two cons.

A HORIZONTALLY mounted thermostatic element expands and contracts lengthwise, controlling a needle valve at the discharge. The element is a bellows filled with alcohol that vaporizes in the presence of steam. Good for super-heated steam and will not freeze. Very large (1m) and prone to corrosion.

Heavy condensate loads can be manually removed using...

low point drains

Three things that steam traps vent

- Air - Carbon Dioxide - Steam Condensate

Name four ways to test a steam trap.

- Observe the discharge downstream of the trap - Temperature differential - Pressure differential - Stethoscope

Three factors determining magnitude of water hammer shock.

- Temperature differential between steam and cooler condensate - Diameter of the pipe - Amount of condensate in the pipe

4 places where condensation can accumulate

- Upstream of the connection to a steam riser - At the ends of steam header mains - Ahead of expansion joints and bends - Inlets to steam valves and regulators

Three causes of flow induced water hammer

- quick opening of liquid valve - quick closing of liquid valve - a fast motor trip

CONTROLLED DISK

Good with superheated steam and very durable. Low condensate capacity and needs a good temperature differential.

THERMOSTATIC: Describe method of operation, two pros, two cons.

A VERTICALLY mounted thermostatic element expands and contracts lengthwise, controlling a needle valve at the discharge. The element is a bellows filled with alcohol that vaporizes in the presence of steam. Can drain large amounts of air and steam for its small size, and will not freeze. Vulnerable to water hammer and corrosion, and cannot be used with superheated steam as it will overheat.

What is steam flow induced water hammer?

A slug of water is produced and propelled by the steam at (toomany)m/s, which can produce incredible pressures once it hits a valve or a 90° bend.

IMPULSE: Describe method of operation

An oddly shaped piston allows itself to be lifted by denser, low-velocity condensate but will seal itself quickly when hot steam flows through it at high speed. NOT A FUNCTION OF TEMPERATURE

2 known types of steam separator

Baffle-type and Centrifugal Type

What is condensate induced water hammer?

Bubbles of steam are ensnared in the condensate and condense fast enough to send shockwaves through the system.

INVERTED BUCKET: Describe method of operation, two pros, two cons.

Condensate arrives under an inverted bucket, which stays down and keeps the discharge valve open. Steam, Air and CO2 will cause the bucket to float, closing the discharge. Good for super-heated lines and can withstand water hammer. Can become air-locked and is vulnerable to freezing.

In a steam system, the greatest rate of steam condensate production will occur...

During warm-up.

BALL FLOAT: Describe method of operation, two pros, two cons.

Has two valves. One thermostatic vent at the top to vent air and CO2 on startup (seals once steam hits it), and a float valve on the bottom to let condensate out when it rises. Good for a wide range of loads, and will not become air locked. Vulnerable to watter hammer and superheated steam (the bellows). Will also freeze if not properly traced.

name seven types of steam traps

I LIT BBC - Inverted bucket - Liquid expansion - Impulse - Thermostatic - Ball float - Bi-metallic - Controlled disc

How often should traps be serviced? What three things must be done?

Once a year, check for corrosion/wear in all components, clean everything, and replace worn parts and all gaskets.

BI-METALLIC

Temperature actuated bi-metallic strip bends and seals a needle valve when heated. Rarely used due to low capacity and poor sealing.