One MCM is equivalent to 1000 circular mils. For comparison, 1 MCM equates to 0.5067 square mm, so for many purposes , a ratio of 2MCM to 1mmsq can be used with a 1.3% (very small) error.

Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 124–38–9

NIOSH REL: 5,000 ppm (9,000 mg/m3) TWA,

30,000 ppm (54,000 mg/m3) STEL

Current OSHA PEL: 5,000 ppm (9,000 mg/m3) TWA

1989 OSHA PEL: 10,000 ppm (18,000 mg/m3) TWA,

30,000 ppm (54,000 mg/m3) STEL

Basis for original (SCP) IDLH: The chosen IDLH is based on the statements by ACGIH [1971] that a 30-minute exposure at 50,000 ppm produces signs of intoxication, and a few minutes of exposure at 70,000 ppm and 100,000 ppm produces unconsciousness [Flury and Zernik 1931]. AIHA [1971] reported that 100,000 ppm is the atmospheric concentration immediately dangerous to life. In addition, Hunter [1975] noted that exposure to 100,000 ppm for only a few minutes can cause loss of consciousness.

OSHA PEL
8-hour TWA
(ST) STEL
(C) Ceiling
Peak
NIOSH REL
Up to 10-hour TWA
(ST) STEL
(C) Ceiling
ACGIH TLV©
8-hour TWA
(ST) STEL
(C) Ceiling
CAL/OSHA PEL
8-hour TWA
(ST) STEL
(C) Ceiling
Peak
PEL-TWA
5000 ppm (9000 mg/m³)

This calculator determines the absolute pressure at the pump impeller. NPSHA must exceed the NPSHR (net positive suction head requirement specified by the pump manufacturer or caviation and/or loss of prime will occur.

Nylon is one of the oldest and most commonly used thermoplastics but there still seems to be a lot of confusion about properly drying nylon and in general about how nylon is affected by moisture. //

You could use a nylon 12 which does not absorb as much moisture but Nylon 12 is really expensive.

The first form calculates the pressure or friction loss along a given length of pipeline with a specified inside diameter. The second form calculates the minimum pipe size to limit pressure loss to a specified value.

Additional friction pressure losses occur due to fittings. These losses in-effect add extra additional length to the total pipeline. Use this calculator to estimate how much additional length needs to be added to the overall pipe length below in order to estimate these additional losses. Learn more about the units used on this page.

All types of resistors have their own resistor symbols which are used when a circuit diagram is drawn. This page will explain the different standards which are used for resistor symbols and display the most common symbols.

A thread of 20 Survival Tips And Tricks You Might Not Have Known Before.

Sold in sets of 8 container corner castings (or individually)

Meets the ISO Standard (ISO 1161) for Container Corner Castings with Regard to Dimensions

There are 2 each of 4 different marine shipping container corner castings per set:

Bottom Left, Bottom Right and Top Left and Top Right

How many foot of water in 1 psi? The answer is 2.3066587368787. We assume you are converting between foot of water [4 °C] and pound/square inch.

• 1 foot of water to psi = 0.43353 psi
• 5 foot of water to psi = 2.16764 psi
• 10 foot of water to psi = 4.33528 psi
• 20 foot of water to psi = 8.67055 psi
• 30 foot of water to psi = 13.00583 psi
• 40 foot of water to psi = 17.3411 psi
• 50 foot of water to psi = 21.67638 psi
• 75 foot of water to psi = 32.51456 psi
• 100 foot of water to psi = 43.35275 psi

Have you ever had a teacher who was very smart but terrible at teaching? An expert who used so much jargon you could not follow their explanation? This is called the “curse of knowledge”, a term coined in 1989 by economists Colin Camerer, George Loewenstein, and Martin Weber.

It’s a cognitive bias that occurs when someone incorrectly assumes that others have enough background to understand. For example, your smart professor might no longer remember the challenges a young student faces when learning a new subject. And the expert might overlook the need to simplify concepts, assuming everyone knows what they know. //

You can avoid the negative effects of the curse of knowledge by constantly questioning your assumptions as to how much exactly your audience knows.
Curse of Knowledge - Mitigating Strategies

• Get to know your audience. Try to know how much they know. If you’re talking to a friend or colleague, assess the extent of their knowledge before starting your explanation. If you’re talking to potential customers, ask a few questions before starting your sales pitch.
• Simplify your language. Don’t hide behind jargon and complex terminology. Use simple language and clear examples to make your point easier to understand even with limited knowledge.
• Use storytelling. Stories can make information more relatable and memorable. Relate complex concepts to familiar experiences. Analogies and metaphors can also make abstract ideas more concrete and understandable.
• Show, don’t tell. A picture can be worth a thousand words. Instead of a lengthy explanation, see if you can create a visual, a graph, or an illustration that conveys the same content in a more accessible way.
• Engage in active teaching. Encourage questions and discussions. Pause at every step to ensure the person is following. By engaging your audience, you can better gauge their level of understanding and adjust your explanations accordingly.

What’s great about simplifying your explanations is that it reinforces your own knowledge. If you can’t explain something without using complicated jargon, you’re probably not as familiar with it as you think. Making the effort to explain concepts in simpler terms ensures you truly understand them.

Welcome to Fourmilab's calendar converter! This page allows you to interconvert dates in a variety of calendars, both civil and computer-related.

• Gregorian Calendar
• Julian Day
• Julian Calendar
• Hebrew Calendar
• Islamic Calendar
• Persian Calendar
• Mayan Calendars

A new flashlight for 2008: The Surefire Backup!

I bought this in spring 2008 and it is wonderful. Almost as much light as the L4, 2/3 the size, single 123 cell with an hour at full brightness, almost a day at the dimmer setting, and the beam is narrower so it really throws well. This one light may be all I need!

My 2003 favorite flashlight:

The Fourmilab Units Calculator is based upon the GNU Units utility. It supports expressions in the “Convert” and “To” fields in the same syntax as described in the GNU Units manual. If the To field is left blank, the definition of the unit in the Convert field will be shown in terms of fundamental units. Entering “?” in the To field shows all standard units with the same dimensions as the expression in the Convert field. A total of 3460 linear units, 109 nonlinear units, and 109 prefixes are defined.

The shipping container ecosystem is governed by requirements that determine almost everything about them. In a previous article, we covered all the common (and some not-so-common) shipping container dimensions. But below, we’ll focus on how containers are described, classified, and constructed.

Convert between Bytes, KB, MB, GB, TB and KiB, MiB, GiB, TiB

ASCII Table

the salt spray chamber pumps a 5% salt fog solution into its atmosphere for the duration of the test, which rapidly accelerates corrosion. //

• The salt spray environment is much more aggressive and concentrated than even a marine setting (the salt concentration of the ocean is roughly 3%).
• Salt spray tests for many common platings and coatings can last multiple days – with some tests lasting 500 hours or more before the parts begin to rust – while stainless steel parts can begin to exhibit signs of rust in as little as a few hours of exposure. Per ASTM A967 and A380, stainless parts are shown to be properly passivated if they resist corrosion in salt spray for just 2 hours.
• Stainless steel performs relatively poorly in salt spray because the constant exposure to a harsh environment rapidly erodes the passivation layer and prevents it from reforming. With the passivation layer inhibited, the base material is exposed and the part quickly begins to corrode.

The copper sulfate test is a visual method of determining the existence of free iron in specifically stainless steel. In many cases, the copper sulfate test is used as a pass/fail examination of a passivation process on a part or stock material, but it can also be used as a test to determine if passivation is necessary in the first place. //

http://everyspec.com/MIL-STD/MIL-STD-0700-0799/MIL_STD_753C_1117/

The method is specifically designed to work with stainless steel alloys with a minimum of 16% chromium as stated in the document.

The procedure is as follows:

1. Prepare test solution – Dissolve 8 grams of copper sulfate in 500 ml of distilled water in which 2 – 3 ml of sulfuric acid has been added.

This will take approximately 5 minutes and should be mixed completely before using. It is noted in the documentation that solutions older than 2 weeks shall not be used for the test. The dilution by weight of the test is 1.6% which is on the lower end of the copper sulfate solution dilution.

2. Swab the surface to be inspected with test solution – keep surface wet for a period of 6 minutes.

3. Carefully rinse and dry the surface such that no copper deposits are removed.

4. Copper deposits indicate the presence of metallic iron.

• Multiply the volume in cubic feet by 62.44 to obtain total pounds of water
• 2 ppm is 0.000002 for maintenance
• 4 ppm is 0.000004 for shock reduction

Therefore, to calculate the amount of Copper Sulfate Pentahydrate to treat 1 acre-foot of water (43,560 cu ft) with 2 ppm Copper Sulfate, the calculation would be:

 43,560 * 62.44 = 2,719,886.4 * 0.000002 = 5.44 lbs. Copper Sulfate

Waterscapes & Fountains:

Dissolve 1/4lb CuSO4 in one gallon of water for every 7500 gallons

Swimming Pools:

2lbs (4ppm) per 60,000 gals (8,000 cu ft) to reduce algae, 1lb (2ppm) for maintenance