Knowledge

Hydrostatic Head

Ian — Thu, 08 Oct 2009 16:57:05 GMT

Current revision posted to Knowledge by Ian on 08/10/2009 17:57:05

Hydrostatic head, what does it mean?

Hydrostatic head is used to define how waterproof a fabric is. A column of water will exert a pressure on the fabric, as the height of this column is increased eventually water will penetrate through the fabric. The height at which this happens will be the fabrics hydrostatic head.

Heavy wind or driving rain will exert more pressure on a fabric therefore a higher hydrostatic head is required to stop the water from penetrating. Likewise the ground sheet of a tent will require a higher hydrostatic head as the weight from being walked/sat on will increase the pressure of the water underneath.

What does this tell me about the fabric?

It tells you how waterproof the fabric is. For example a lightweight waterproof coat designed for use in showers will have a low (typically 1200mm) hydrostatic head. Whereas the ground sheet of a tent where the pressure of you walking/ sitting in it could force water through (typically 10,000 mm).

Why not just use the highest possible?

Normally the higher the hydrostatic head the less breathable and heavier the fabric is. If you are a marathon runner there is no point having a super waterproof jacket if you just get soaked by your own sweat. Therefore a compromise needs to be made. Likewise if the fabric is for the ground sheet of a tent designed for family camping, the weight is not so much of an issue.

How can you test a fabrics hydrostatic head?

Find a suitable piece of pipe. For example drain pipe
Tape the fabric sample to one end of pipe. Don’t forget to ensure the “outside” of the fabric is facing inside the pipe as this is where the water will be.
Stand up the pipe with the fabric at the bottom.
Slowly fill the pipe with water until it starts to seep through the fabric. If it starts to come out round the edges you tape isn't strong enough.
Measure the height of the column of water in millimetres. This is the hydrostatic head.

Characteristics of dynamic climbing ropes

neil — Wed, 27 May 2009 12:13:49 GMT

Current revision posted to Knowledge by neil on 27/05/2009 13:13:49

Characteristics of a dynamic climbing ropes

Filed under: Climbing Rope

Number of bobbins

The sheath encircles and protects the rope’s core, it is the visible part. It is formed from groups of filaments: each group woven from a bobbin. For equal diameter, a larger number of bobbins give better dynamic characteristics, and a smaller number of bobbins give better abrasion resistance. Thus one chooses a single rope of 48 bobbins construction for dynamic performance ( Beal TOP GUN II) or of 32 bobbins to maximise abrasion resistance (Wall Master V) by using thicker filament.

Diameter and weight

Ropes of large diameter generally have a longer active life, but they are heavier and less manageable. On routes where weight and ease of running are important, it may be preferable to choose a thinner rope.

Impact force

Values required by the Standard:

Single rope: Impact force lower than 12kN holding the first factor 1.77 fall with a mass of 80kg.
Double rope: Impact force lower than 8kn holding the first factor 1.77 fall with a mass of 55kg.
Twin rope: Impact force lower than 12kN holding the first factor 1.77 fall with a mass of 80kg, on two strands.

The impact force printed in the technical notice must not be lower than the poorest result found by the certifying laboratory.

Number of UIAA Falls Laboratory

To satisfy the Standards, single rope must withstand 5 successive factor 1.77 falls with a mass of 80kg; double rope 5 successive falls with a mass of 55kg; twin ropes 12 successive falls with a mass of 80kg on two strands. The number of falls shown on the technical notice must not be higher than the poorest result found by the certifying laboratory.

Sheath slippage

The core and the sheath of the rope are two independent components which have a tendency, if the construction is not carefully matched, to dislocate and slide against each other. The sheath deforms and little by little under the effect of the descender it bunches, creating a slack zone around the core and bulge points: the sock effect. This phenomenon results in more rapid wear, particularly with top-roping or other intensive use, it also risks jamming in descenders or belay devices.

Dynamic elongation

This is the stretch of the rope during the first UIAA test fall. It must be less than 40%.

Static elongation

Measured under a load of 80kg it must not exceed 10% for single rope, 12% for double rope, and 10% for two strands of twin rope together

Characteristics of a dynamic climbing ropes

Ian — Mon, 18 May 2009 17:30:30 GMT

Revision 1 posted to Knowledge by Ian on 18/05/2009 18:30:30

Number of bobbins

Diameter and weight

Impact force

Values required by the Standard:

Single rope: Impact force lower than 12kN holding the first factor 1.77 fall with a mass of 80kg.
Double rope: Impact force lower than 8kn holding the first factor 1.77 fall with a mass of 55kg.
Twin rope: Impact force lower than 12kN holding the first factor 1.77 fall with a mass of 80kg, on two strands.

The impact force printed in the technical notice must not be lower than the poorest result found by the certifying laboratory.

Number of UIAA Falls Laboratory

Sheath slippage

Dynamic elongation

This is the stretch of the rope during the first UIAA test fall. It must be less than 40%.

Static elongation

Measured under a load of 80kg it must not exceed 10% for single rope, 12% for double rope, and 10% for two strands of twin rope together

Replacing the Jetboil PCS stove igniter

Ian — Thu, 21 May 2009 16:57:25 GMT

Current revision posted to Knowledge by Ian on 21/05/2009 17:57:25

Replacing the Jetboil PCS stove igniter

Filed under: Stoves, Jetboil

How to replace the piezo igniter on the Jetboil Personal Cooking System.

CAUTION! Do not attempt this while the Jetboil burner is hot. The burner will remain hot even after the cup cools. Allow the Jetboil burner to cool before beginning.

Grip the burner head (the disk that flames come out of), and turn it counter clockwise until it, and the metallic base plate it’s attached to, come loose.
Now comes the fun part: now that the burner is unscrewed from the valve, you’ll need to rotate and twist the burner and base plate to clear the igniter. Bend the igniter if you need to- you’re replacing it!
Once you’ve separated the burner and base plate from the igniter, pull straight up on the igniter to release it from its clips.
Insert the new igniter (which may look different from your old igniter) and press until it “snaps” in place.
Doing the reverse of step (2), we need to get the burner and base-plate back into position, with the igniter popping up through the hexagonal hole in the base-plate.
Press the igniter button a few times- you should see a spark. If not, you might need to bend the silver igniter wire. Its tip should be approximately 1/4" away from the burner head, or perhaps a bit closer.
Make a cup of coffee or some soup, and enjoy!

Replacing the Jetboil PCS igniter

Ian — Thu, 21 May 2009 16:50:38 GMT

Revision 3 posted to Knowledge by Ian on 21/05/2009 17:50:38

Replacing the Jetboil PCS igniter

Filed under: Stoves, Jetboil

How to replace the piezo igniter on the Jetboil Personal Cooking System.

CAUTION! Do not attempt this while the Jetboil burner is hot. The burner will remain hot even after the cup cools. Allow the Jetboil burner to cool before beginning.

Grip the burner head (the disk that flames come out of), and turn it counter clockwise until it, and the metallic base plate it’s attached to, come loose.
Now comes the fun part: now that the burner is unscrewed from the valve, you’ll need to rotate and twist the burner and base plate to clear the igniter. Bend the igniter if you need to- you’re replacing it!
Once you’ve separated the burner and base plate from the igniter, pull straight up on the igniter to release it from its clips.
Insert the new igniter (which may look different from your old igniter) and press until it “snaps” in place.
Doing the reverse of step (2), we need to get the burner and base-plate back into position, with the igniter popping up through the hexagonal hole in the base-plate.
Press the igniter button a few times- you should see a spark. If not, you might need to bend the silver igniter wire. Its tip should be approximately 1/4" away from the burner head, or perhaps a bit closer.
Make a cup of coffee or some soup, and enjoy!

Replacing the Jetboil PCS igniter

Ian — Thu, 21 May 2009 16:42:58 GMT

Revision 2 posted to Knowledge by Ian on 21/05/2009 17:42:58

Replacing the Jetboil PCS igniter

Filed under: Stoves, Jetboil

How to replace the piezo igniter on the Jetboil Personal Cooking System.

CAUTION! Do not attempt this while the Jetboil burner is hot. The burner will remain hot even after the cup cools. Allow the Jetboil burner to cool before beginning.

Grip the burner head (the disk that flames come out of), and turn it counter clockwise until it, and the metallic base plate it’s attached to, come loose.
Now comes the fun part: now that the burner is unscrewed from the valve, you’ll need to rotate and twist the burner and base plate to clear the igniter. Bend the igniter if you need to- you’re replacing it!
Once you’ve separated the burner and base plate from the igniter, pull straight up on the igniter to release it from its clips.
Insert the new igniter (which may look different from your old igniter) and press until it “snaps” in place.
Doing the reverse of step (2), we need to get the burner and base-plate back into position, with the igniter popping up through the hexagonal hole in the base-plate.
Press the igniter button a few times- you should see a spark. If not, you might need to bend the silver igniter wire. Its tip should be approximately 1/4" away from the burner head, or perhaps a bit closer.
Make a cup of coffee or some soup, and enjoy!

Replacing the Jetboil PCS igniter

Ian — Thu, 21 May 2009 16:37:09 GMT

Revision 1 posted to Knowledge by Ian on 21/05/2009 17:37:09

CAUTION! Do not attempt this while the Jetboil burner is hot. The burner will remain hot even after the cup cools. Allow the Jetboil burner to cool before beginning.

Grip the burner head (the disk that flames come out of), and turn it counter clockwise until it, and the metallic base plate it’s attached to, come loose.
Now comes the fun part: now that the burner is unscrewed from the valve, you’ll need to rotate and twist the burner and base plate to clear the igniter. Bend the igniter if you need to- you’re replacing it!
Once you’ve separated the burner and base plate from the igniter, pull straight up on the igniter to release it from its clips.
Insert the new igniter (which may look different from your old igniter) and press until it “snaps” in place.
Doing the reverse of step (2), we need to get the burner and base-plate back into position, with the igniter popping up through the hexagonal hole in the base-plate.
Press the igniter button a few times- you should see a spark. If not, you might need to bend the silver igniter wire. Its tip should be approximately 1/4" away from the burner head, or perhaps a bit closer.
Make a cup of coffee or some soup, and enjoy!

Reversing a battery's polarity is dangerous

Ian — Mon, 18 May 2009 17:29:32 GMT

Current revision posted to Knowledge by Ian on 18/05/2009 18:29:32

When inserting the batteries in to the battery case carefully follow the diagram on the battery case or in the instructions in regards to the batteries polarity.

A battery inserted the wrong way can explode.

If the polarity of one battery is reversed in the battery case (with two (+) ends in contact with one another or two (-) ends in contact with each other) it's will be charged by the other batteries.
This causes a chemical reaction inside the reversed battery. Within a few minutes, the battery can leak explosive gases and/or extremely corrosive liquids.
There is a danger of explosion and chemical burns.

Indication: a weak level of light

If a torch with fresh batteries emits a weak light, it could mean that one or more of the batteries are reversed.

What to do?

Immediately turn off the headlamp and check the polarity of the batteries.
Precautions must be taken when opening the battery case in the event a leak has already occurred or occurs while opening the case. Wear protective gloves and goggles. If you are unsure do not open the case, especially if you are in a remote location. Situations like this are a good reason for carrying a spare torch, like the Petzl e+lite.
If you come in contact with the liquid from the batteries, immediately rinse the affected area with running water and seek medical help.

Using Lithium Batteries with LED Torches

Ian — Mon, 18 May 2009 17:28:51 GMT

Current revision posted to Knowledge by Ian on 18/05/2009 18:28:51

Limitations on use of AA/LR6 and AAA/LR03 Lithium batteries with headlamps.

This information does not apply to the Petzl e+Lite which was designed to work with CR2032 Lithium batteries.

Lithium batteries are lighter and give longer burn times at low temperature than traditional alkaline batteries.
Recent advances in the performance characteristics of Lithium batteries (especially their higher output during discharge), mean they can cause the lamp to overheat and possibly damage the LEDs.

Therefore we recommend you do not use lithium batteries in any torch that uses LEDs unless the manual specifically advises to (eg Petzl e+lite or Petzl Signal).
Lithium batteries can be used with incandescent bulbs but will reduce their lifespan.

LP-Gas or Multi-Fuel Stove

Ian — Mon, 18 May 2009 17:28:08 GMT

Current revision posted to Knowledge by Ian on 18/05/2009 18:28:08

LP-Gas or Multi-Fuel Stove

Filed under: Stoves

LP-Gas Stoves

For most camping trips especially in the UK an LP-Gas stove is sufficient. These stoves normally use a mix of Propane and Butane as the fuel. Gas stoves are generally easier to use, cleaner and lighter than Multifuel stoves.

Most modern lightweight gas stoves use EN417 gas canisters. These canisters have a standard threaded, re-sealable valve so the stoves will fit any canister that complies with this standard. These fuel canisters are readily available, easy to change and store. Note: EN417 type 200 pierce able gas canisters are not compatible.

The disadvantage of a gas stove compared to a multifuel stove is their performance suffers in the cold. This is explained in more detail in our Knowledge Article “[Using “Using a gas powered stove in cold weather]” Also in some foreign countries it can be difficult to get hold of gas canisters.

Multi-Fuel Stoves

A multi-fuel stove has the flexibility to run on several different liquid fuels (some will even work with LP-Gas as well). This is a big advantage where travelling when gas may not be readily available. Liquid fuel stoves will also cope with the cold much better than LP-Gas stoves so are ideal for use in the colder months in the UK.

Using a multi-fuel stove is slightly more complicated than a gas stove. First off, the fuel has to be pressurised in order to make the stove as hot as possible. The gas in a gas bottle is already pressurised when you buy it from the shop, but the liquid fuel you put in your fuel bottle is not. Multi-fuel stoves have a built in pump so you can pressurise the bottle yourself.

You also need to preheat the stove for a short time using a squirt of fuel. This involves heating up the burner to such an extent that the fuel is vaporised as it passes through the burner’s nozzle. Vaporised fuel burns efficiently with a blue flame and a hissing sound.

Where possible, it is advisable to run a multi-fuel stove on white gas such as Colman white gas or Optimus Artic fuel. These fuels are specifically designed to work with multi-fuel stoves and burn very clean, with a high energy output. Be careful when using Petrol, apart from being highly volatile, it contains additives which give off nasty fumes when burnt in a stove. Ensure your cooking area is well ventilated. Heavier fuels such as Diesel or Aviation fuel will produce a lot of soot and the stove will quickly become clogged so it is advisable to familiarise yourself with how to clean your stove in the field. Preheating the stove with a different fuel may help to reduce clogging.

LP-Gas or Multi-Fuel Stove

Ian — Mon, 18 May 2009 17:27:34 GMT

Revision 2 posted to Knowledge by Ian on 18/05/2009 18:27:34

LP-Gas or Multi-Fuel Stove

Filed under: Stoves

LP-Gas Stoves

The disadvantage of a gas stove compared to a multifuel stove is their performance suffers in the cold. This is explained in more detail in our Knowledge Article “Using “[Using a gas powered stove in cold weather]” Also in some foreign countries it can be difficult to get hold of gas canisters.

Multi-Fuel Stoves

LP-Gas or Multi-Fuel Stove

Ian — Mon, 18 May 2009 17:26:40 GMT

Revision 1 posted to Knowledge by Ian on 18/05/2009 18:26:40

LP-Gas Stoves

The disadvantage of a gas stove compared to a multifuel stove is their performance suffers in the cold. This is explained in more detail in our Knowledge Article “Using a gas powered stove in cold weather” Also in some foreign countries it can be difficult to get hold of gas canisters.

Multi-Fuel Stoves

Using a gas powered stove in cold weather

Ian — Mon, 18 May 2009 17:27:18 GMT

Current revision posted to Knowledge by Ian on 18/05/2009 18:27:18

Using a gas powered stove in cold weather

Filed under: Stoves

All canister stoves suffer a performance drop in cold weather. The colder the fuel, the lower the vapour pressure, and the lower the burner output. The result can be noticeably longer boil times and difficulty lighting the burner with the built-in piezoelectric igniter. Using a fuel canister containing propane helps mitigate cold weather problems.

The following tips should help improve your stoves performance in cold weather;

Keep the canister in a warm pocket between uses and remove it immediately prior to heating your food.
Carry an extra canister, keep it warm and swap out with a cold one when necessary.
Always carry matches or a lighter as backup.

Using a gas powered stove in cold weather

Ian — Mon, 18 May 2009 17:27:08 GMT

Revision 1 posted to Knowledge by Ian on 18/05/2009 18:27:08

The following tips should help improve your stoves performance in cold weather;

Keep the canister in a warm pocket between uses and remove it immediately prior to heating your food.
Carry an extra canister, keep it warm and swap out with a cold one when necessary.
Always carry matches or a lighter as backup.

Canister Mount or Remote Fuel Gas Stove

Ian — Mon, 18 May 2009 17:23:11 GMT

Current revision posted to Knowledge by Ian on 18/05/2009 18:23:11

LP Gas Stoves can either be mounted directly to the gas canister or remotely via a pipe.

Canister Mount Gas Stoves

Canister mounted stoves are more compact and lightweight but are less stable, especially with large heavy pots. They are ideal for lightweight trips or lunch stops when you are not cooking large volumes of food.
To increase the stability of your canister mounted stove you can use the Primus Stove Foot Rest. This compact 3 legged foot rest increases the stability of your stove when using large pots or cooking on uneven surfaces.

Remote Fuel Gas Stoves

By moving the gas canister from under the stove, remote fuel stoves are lower and more stable, especially with heavier pots. Whilst less compact, this makes the stove idea for base camp cooking for several people.