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. All, 4. Hydraulics, Calculators

NPSH – Net Positive Suction Head

Posted on May 2, 2019December 9, 2023 by JAB

02
May

NPSH - Net Positive Suction Head

Calculation
Comments

PIPE PRESSURE DROP DENSITY

The NPSH is related to the problem of cavitation. Cavitation means that the liquid pumped vaporizes within the pump which causes breakdown of suction column and head, loud noise, heavy vibration leading to erosion or pitting and possibly destruction of the impellers. The condition for operation without cavitation is:

NPSHa > NPSHr

Where:

NPSHa: NPSH available, of the plant.

NPSHr: NPSH required, of the pump. Lower value of NPSHr means greater the suction capability.

Usually is used a safety allowance of 0.5m.

$NPSHa=10^{5}cdot frac{( P-Vp )}{rho cdot g}pm S-H$

P: Gas pressure. If the suction tank is open the gas pressure correspond to the atmospheric pressure (1 bar).

Vp: Vapour pressure of the fluid pumped at a given temperature.

ρ: Density of the fluid pumped.

g: gravitational constant 9.81 m/s²

S: Suction head. Vertical distance between suction tank and pump center line. (- ) for operation under suction lift conditions and (+) for operation under flooded suction conditions.

H: Head loss for the maximum flow in pipes, bends and valves on the suction side due to friction.

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. All, 4. Hydraulics, Calculators

Pipe pressure drop

Posted on April 25, 2019December 9, 2023 by JAB

25
Apr

Pipe pressure drop

Density Dynamic viscosity Surface roughness

Darcy friction factor formulae

Neutrium – Theory

This calculator performs Pressure Drop Calculations for pipework. Additionaly, related parameters such as Reynolds, fluid velocity, average residence time, etcetera are presented. The Pressure Drop calculation takes into account other components as well. It requests the user for input about bends, elbows and other appendages/equipment components, which induce extra pressure loss. The program represents the total resistance in terms of equivalent pipe length values.

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. All, Info, Mechanical elements, Tables

Thread types

Posted on March 27, 2019May 16, 2019 by JAB

27
Mar

Thread types

Types

Symbol	Angle	Parallel/tapered	Standard	Description	Application
A/B	60°	Parallel	DIN 4503, ISO 1222	Tripod connection thread	Connections to photografic equipment.
ACME-C	29°		ANSI B1.5 (1977)	Acme thread centralizing
ACME-G	29°		ANSI B1.5 (1977)	Acme thread general purpose
AMO	55°		ANSI B1.11 (1958)	American standard microscope objective thread
ANPT	60°		MIL-P-7105	Aeronautical national form taper pipe thread
API	60°			American national taper form thread for petroleum installations
BA	47°30'		BS93 (1951)	British association thread
BSC	60°		BS811 (1950)	British norm thread for bicycles
BSF	55°	Parallel	BS84 (1956)	Whithworth fine thread
BSW	55°	Parallel	BS84 (1956)	Whithworth coarse thread
E	-		DIN 40400, DIN 49612, DIN 49610, DIN 49625	Edison form thread	Electrical thread.
EG M	60°	Parallel	DIN 8140-2	Metric ISO thread for helical coil wire screw thread inserts	For wire thread inserts.
EG-UNC	60°	Parallel	MS 33537	Unified coarse thread series for helical coil wire screw thread inserts
EG-UNF	60°	Parallel	ASME B18.29.1	Unified fine thread for helical coil wire screw thread inserts
FG	60°	Parallel	DIN 79012	Bicycle thread	For cycles and motor-scooters.
G	55°	Parallel	DIN ISO 228, DIN 6630	Pipe parallel ISO thread	For pressure tight joints are not made on the thread. External and internal pipe thread. Packaging; external thread for barrels.
G	55°	Parallel	BS2779 (1973)	Pipe whitworth thread (BSP)parallel
Gf		Tapered	DIN 4930	Round tapered thread	Tubes and tunneling
Gg	60°	Tapered (1:16)	DIN 4941	Tapered thread	For drill pipes in water and rock drilling, mining.
Gg	30°-30°	Tapered (1:4)	DIN 20314	Tapered thread	For drill pipes in water and rock drilling, mining.
GL	30°-60°	Parallel	DIN 168-1	Cylindrical round thread	For glass containers.
Glasg	30°-50°	Parallel	DIN 40450	Glasg thread for glass	Electric industry: glass fittings, protection glasses.
HA-HB			DIN 58810	Bone screw thread	For surgical implants, external and internal thread.
KT	20°	Parallel	DIN 6063	Trapezoidal thread	Preferably for packages made of plastics.
LN	60°	Parallel	LN 9163, EN 2158	ISO Metric thread for aviation	Aviation and aerospace.
M	60°	Parallel	DIN 13, DIN 14, ISO 68, DIN 6630, LN 9163, DIN 2510	Metric coarse ISO thread	General engineering, watches, fine work, packaging; external thread for barrels, aviation, aerospace and bolted connections with reduced shank.
M	60°	Tapered (1:16)	DIN 158	Taper metric ISO thread	Plugs and grease nipples.
MF	60°	Parallel	DIN 13, DIN EN 60423	Metric fine ISO thread
MFS	60°	Parallel	DIN 8141-1	ISO Metric thread for tight fit
MJ	60°	Parallel	DIN ISO 5855	Metric ISO thread for aeronautics	Aviation and aerospace.
N	60°		ANSI B1.1 (1960)	American national 8-12-16 TPI pitch series (8N, 12N, 16N)
N-BUTT	45°+5°		ANSI B1.9 (1973)	American BUTTRESS thread
NC	60°		ANSI B1.1 (1960)	American national coarse thread series
NEF	60°		ANSI B1.1 (1960)	American national extra fine thread series
NF	60°		ANSI B1.1 (1960)	American national fine thread series
NGO	60°		ANSI/ASME-B1.20.1 (1983)	National gas outlet thread (specify RH or LH)
NGS	60°		ANSI/ASME-B1.20.1 (1983)	National gas straight thread
NGT	60°		ANSI B57.1 (1977)	National gas taper thread (see also SGT)
NH	60°		ANSI B2.4 H28 (1966)	American national firehouse and hose coupling thread
NPS	60°			American standard straight pipe thread NSPC & NPSM
NPSC	60°		ANSI/ASME-B1.20.1 (1983)	American standard straight pipe thread in pipe couplings (marked NPS)
NPSF	60°		ANSI B1.20.3 (1976)	Dryseal American standard internal straight pipe thread (fuel)
NPSH	60°		ANSI/ASME-B1.20.1 (1983)	American standard straight pipe thread for hose couplings
NPSI	60°		ANSI B1.20.3 (1976)	American standard intermediate internal straight pipe thread
NPSL	60°		ANSI/ASME-B1.20.1 (1983)	American standard straight pipe thread for loose-fitting mechanical joints
NPSM	60°		ANSI/ASME-B1.20.1 (1983)	American standard straight pipe thread for free-fitting mechanical joints
NPT	60°	Tapered (1:16)	ANSI/ASME-B1.20.1 (1983)	American standard tapered pipe thread	For threads with dryseal material.
NPTF	60°	Tapered (1:16)	ANSI B1.20.3 (1976)	American standard tapered pipe thread (fuel)	For threads without dryseal material.
NPTR	60°		ANSI/ASME-B1.20.1 (1983)	American standard taper pipe thread for railing joints (tap market NPT)
NS	60°		ANSI B1.1 (1960)	American national thread special pitches
Pg	80°	Parallel	DIN 40430	Steel electrical conduit thread	For electric installations.
PTF	60°		ANSI B1.20.1 (1976)	Dryseal SAE short taper pipe thread
R	55°	Parallel	DIN 259	Pipe parallel whitworth thread	For pressure tight joints are not made on the thread. Piping, do not use in new designs.
R	55°	Tapered (1:16)	BS21 (1985), DIN EN 10226-1, ISO 7-1, DIN 2999, DIN 3858	External dryseal pipe taper thread (BSPT)	Tapered Whitworth pipe thread where pressure-tight joints are made on the threads.
Rc	55°	Tapered (1:16)	BS21 (1985), DIN EN 10226-1, ISO 7-1	Internal dryseal pipe taper thread (BSPT)	Tapered Whitworth pipe thread where pressure-tight joints are made on the threads.
Rd	30°	Parallel	DIN 405, DIN 20400, DIN 15403, DIN 7273	Rounded thread	General, for mining industry, for lifting hooks, for steel sheet items and related joints.
RMS	55°	Parallel	DIN 58888	RMS-thread	Objective for microscope.
Rp	55°	Parallel	DIN 2999, DIN 3858	Internal dryseal parallel thread	Internal thread for pipes and fittings.
Rp	55°	Parallel	BS21 (1973), DIN EN 10226-1, ISO 7-1	Pipe parallel thread (BSPP)	Cylindrical Whitworth pipe thread where pressure-tight joints are made on the threads.
S	30°+3°	Parallel	DIN 513, DIN 20401	Saw form thread	General. Mining industry.
S	45°	Parallel	DIN 2781	Saw form thread	For machine tools, hydraulic presses.
S	105°	Tapered (7°30')	DIN 71412	Self forming taper external thread	Taper lubricating nipple. Similar to DIN 158 but 105° thread angle.
SB				Manufacturers stovebolt standards thread
SGT	60°		ANSI B57.1 (1977)	Special gas taper thread
SPL-PTF	60°		ANSI B1.20.3 (1976)	Dryseal special taper pipe thread
ST	60°	Parallel	DIN 7970, DIN EN ISO 1478	Sheet metal screw thread	For tapping screws.
STI	60°			Special thread for helical coil wire screw thread inserts
STUB-ACME	29°		ANSI B1.8 (1977)	Stub Acme thread
Tr	30°	Parallel	DIN 103, DIN 380, DIN 263, DIN 6341, DIN 30295	Trapezoidal thread	General, for rail vehicles, for collet chucks.
UN	60°		ANSI B1.1 (1982)	Unified 8-12-16 TPI pitch series
UN-8	60°		ASME B1.1	Unified thread for special diameters and pitches
UNC	60°		ANSI B1.1 (1982)	Unified coarse thread series
UNEF	60°		ANSI B1.1 (1982)	Unified extra fine thread series
UNF	60°		ANSI B1.1 (1982)	Unified fine thread series
UNJ	60°		BS 4048 (1978)	Unified constant pitch with a 0,15011P to 0,18042P controlled root radius
UNJC	60°		BS 4048 (1978), ASME B1.15	Unified coarse thread with a 0,15011P to 0,18042P controlled root radius
UNJEF	60°		BS 4048 (1978)	Unified extra fine thread with a 0,15011P to 0,18042P controlled root radius
UNJF	60°		BS 4048 (1978), ASME B1.15	Unified fine thread with a 0,15011P to 0,18042P controlled root radius
UNM	60°		ASA B1.10 (1958)	Unified miniature thread series
UNS	60°		ANSI B1.1 (1982)	Unified thread special pitches
V	60°			60° "V" thread with truncated crest and root(flatted to the user's specifications)
Vg	60°	Parallel	DIN 7756	Valves thread	Valves for tires.
W	55°	Parallel	DIN 477	Parallel whitworth thread	Cylindrical thread for side connections.
W keg	55°	Tapered (3:25)	DIN 477, DIN EN 144-1, DIN EN 629-1, DIN EN ISO 11116-1	Tapered thread for screw sockets	Gas cylinders, thread for side nozzles.

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. All, 3. Pneumatics, Calculators, Uncategorized

Cylinder air consumption

Posted on March 12, 2019December 9, 2023 by JAB

12
Mar

This calculator is valid for simple and double effect. For simple effect the value provide by the calculator has to be divided by 2.
Leakage is not taken into the calculator.

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. All, Calculators, Forces, Physics

Centrifugal force

Posted on March 7, 2019December 9, 2023 by JAB

07
Mar

Centrifugal force

Calculation
Comments

Centrifugal force is the inertia force that arises in each rotating object. It is only required in a rotating reference frame – or, in other words, when we look at the system from the point of view of the object in motion.

$F=mcdot frac{v^{2}}{R}$

F: the force

m: the mass of the object

v: the velocity

R: the radius

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. All, 2. Electrics

Index of protection

Posted on March 3, 2019December 9, 2023 by JAB

03
Mar

Index of protection

Standards organisations

IEC – International Electrotechnical Commission, publishes international standards for all electrical, electronic, and related technologies. www.iec.ch

NEMA – National Electrical Manufacturers Association, a U.S. trade association sets ratings for environmental sealing. www.nema.org

The IP Rating System describes the ‘degree of protection’ as defined by the International Electrotechnical Commission standard 60529 (IEC60529). IP stands for International Protection, frequently referred to as ‘Ingress Protection’. The degree of protection as defined by the IEC is used to describe:

Protection offered to people against hazardous parts inside an enclosure.
Protection of equipment inside the enclosure against the intrusion of solids.
Protection of equipment inside the enclosure against the ingress of liquids.

The IP code designation consists of the letters IP followed by two numerals, and is sometimes followed by optional letters. The first number is a measure of how well the enclosure can prevent an invasion by solids. The second number indicates the degree of protection against liquids of various pressures, directions and volumes.

The IP rating system does not cover condensation, fungus and harmful vapour so assumptions should not be made that a highly rated switch will be protected.

NEMA considers numerous requirements including corrosion resistance, effects of icing, gasket aging and oil resistance and coolant effects. It is possible to say that a NEMA Type is equivalent to an IP rating but an IP rating is not equivalent to a NEMA Type. The IP code only address requirements for the protection of people, the ingress of solids and the ingress of water. The NEMA Types consider these and also numerous other requirements including:

Construction requirements
Door and cover securement
Corrosion resistance
Effects of icing
Gasket aging and oil resistance
Coolant effects

IP69K

German standard DIN 40050-9 extends IEC 60529 with an additional rating for environmental sealing – IP69K, for high-pressure, high-temperature wash-down applications. Devices must not only be dust tight (IP6X), but also able to withstand high-pressure and steam cleaning. The test is very strict: 80°C water is sprayed through a nozzle at pressures of 8–10 MPa (80–100 bar) and a flow rate of 14–16 Litres/min. The nozzle must be held 10–15 cm from the tested device at angles of 0°, 30°, 60° and 90° for 30 seconds each. The test device sits on a turntable that rotates once every 12 seconds (5 rpm). The IP69K test specification was initially developed for road vehicles, especially construction vehicles and those that need regular intensive cleaning, but also finds use in other intensely hygienic applications (e.g. food industry).

NEMA

In the United States, the National Electrical Manufacturers Association sets the requirements for environmental sealing and its standards are widely used throughout North, Central and South America. The NEMA Standards Publication 250 – 2008 (previously 250 – 2003; 250 – 1997) “Enclosures for Electrical Equipment (1000 Volts Maximum)” defnes enclosures according to their type from 1 to 13. Detailed information on some of the types relevant to HMI components are shown in Table 3.

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. All, Tables

Absolute roughness

Posted on February 1, 2019February 7, 2019 by JAB

01
Feb

Absolute roughness

Pipe Material	Absolute roughness k (mm)
Aluminum new	0,001-0,002
Brass	0,015
Brass new	0,001-0,002
Cast iron new	0,25-0,8
Cast iron slightly rusted	1,5
Cast iron very rusted	3
Cast iron with bitumen layer	0,2
Copper	0,015
Copper new	0,001-0,002
Epoxy, vinyl ester and isophthalic pipe	0,005
Flexible rubber tubing smooth	0,006-0,07
Glass	0,015
Lead	0,015
Lead new	0,001-0,002
Ordinary concrete	0,3-1
PVC and Plastic pipes	0,0015-0,007
Rough concrete	0,3-5
Sheet or asphalted cast iron	0,01-0,015
Smoothed cement	0,3
Stainless steel electropolished	0,0001-0,0008
Stainless steel turned	0,0004-0,006
Stainless steel, bead blasted	0,001-0,006
Steel pipe after longer use	0,2
Steel pipe galvanised	0,15
Steel pipe new	0,04
Steel pipe slightly rusted	0,4
Steel pipe very rusted	3,35
Stretched steel	0,015
Weld steel	0,045
Worn cast iron	0,8-1,5

Absolute Roughness (k) is a measure of pipe wall irregularities. The absolute roughness has dimensions of length and is usually expressed in millimeter (mm) or feet (ft). Absolute Roughness is usually defined for a material and can be measured experimentally. Absolute roughness is important when calculating pressure drop particularly in the turbulent flow regime.

For each pipe material either a single pipe roughness value or a range of roughness values is normally provided by the manufacturer. The roughness value, usually denoted as e or k, is used in the calculating the relative roughness of a pipe against the size of its diameter.

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. All, 6. Packaging and transport

Slings for machinery lifting

Posted on January 30, 2019December 9, 2023 by JAB

30
Jan

Slings for machinery lifting

The minimal Safety factor must be at least equal to:

7:1 for webbing and round slings

4:1 for accessories made of steel

5:1 for the remaining components

Recommendations of use:

Never slide slings under a load. Never leave a load laying on a sling.
Never knot slings or never use twisted slings.
Protect from any sharp edges.
Never use knotted, cut or damaged slings without tags.
Check the weight of the load. Never overload.
Use slings in arrange of temperature -40°C to +100°C.
Reference to the standards: EN 1492-1, EN 1492-2, DIN 61360, CEN Norm.

Eye opening angle

The minimum length for the eyes is fixed by standard EN 1492-1 to 3 times the width of the sling for widths up to 150mm; 2,5 times for width above 150mm. These lengths have been fixed to respect an angle usage between 10° to 20° when using the slings. An excessive eye opening angle will open the sling and a small eye opening angle will generate a bending stress at the lifting axis.

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. All, 7. Basics, Calculators, Physics

Mass moments of inertia calculator

Posted on December 3, 2018December 9, 2023 by JAB

03
Dec

Mass moments of inertia calculator

The moment of inertia, otherwise known as the angular mass or rotational inertia, is a measure of an object’s resistance to change in rotation direction. Moment of Inertia has the same relationship to angular acceleration as mass has to linear acceleration.

Moment of Inertia of a body depends on the distribution of mass in the body with respect to the axis of rotation

For a point mass the Moment of Inertia is the mass times the square of perpendicular distance to the rotation reference axis and can be expressed as

I = m r²

Where

I = moment of inertia (kg m²)

m = mass (kg)

r = distance between axis and rotation mass (m)

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. All, Tables

Friction coefficients

Posted on November 26, 2018April 12, 2020 by JAB

26
Nov

Friction coefficients

Friction
Coments

Material 1	Material 2	Static dry	Static lubricated	Dynamic dry	Dynamic lubricated
Steel	Steel	0.5	0.1	0.4	0,1-0,05
Steel	Cast iron	0.2	0.1	0.18	0,1-0,05
Steel	Cu-Sn alloy	0.2	0.1	0.1	0,06-0,03
Steel	Pb-Sn alloy	0.15	0.1	0.1	0,05-0,03
Steel	Polyamide	0.3	0.15	0.3	0,12-0,03
Steel	PTFE	0.04	0.04	0.04	0.04
Steel	friction lining	0.6	0.3	0.55	0,3-0,2
Steel	Wood	0.55	0.1	0.35	0.05
Wood	Wood	0.5	0.2	0.3	0.1
Cast iron	Cu-Sn alloy	0.25	0.16	0.2	0.1
Rubber	Cast iron	0.5		0.45
Rolling element	Steel				0,003-0,001
Aluminum	Aluminum	1,05-1,35	0.3	1.4
Aluminum	Mild steel	0.61		0.47
Brass	Cast iron			0.3
Bronze	Cast iron			0.22
Cast iron	Cast iron	1.1		0.15	0.07
Copper	Stainless steel (304)	0.23		0.21
Glass	Glass	0,9-1	0,1-0,6	0.4	0,09-0,12
Glass	Metal	0,5-0,7	0,2-0,3
Graphite	Graphite	0.1	0.1
Graphite	Steel	0.1	0.1
Nylon	Nylon	0,15-0,25
Polystyrene	Polystyrene	0.5	0.5
Polystyrene	Steel	0,3-0,35	0,3-0,35
Steel	Brass	0.35	0.19
Mild steel	Brass	0.51		0.44
Mild steel	Cast iron		0.18	0.23	0.13
Teflon	Steel	0.04	0.04		0.04
Titanium Alloy	Aluminium Alloy	0.41		0.38
Titanium Alloy	Titanium Alloy	0.36		0.3
Titanium Alloy	Bronze	0.36		0.27

The friction coefficient depend on several factors: contact pressure, surface roughness, temperature, sliding velocity, type of lubricant and level of contamination.
Static coefficients of friction are higher than the dynamic or kinetic values.

NPSH - Net Positive Suction Head

Pipe pressure drop

Thread types

Cylinder air consumption

Centrifugal force

Index of protection

Absolute roughness

Slings for machinery lifting

Eye opening angle

Mass moments of inertia calculator

Friction coefficients

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