Misplaced Pages

#193806

70-491: The air handling function of a PLSS is similar to that of a diving rebreather , in that exhaled gases are recycled into the breathing gas in a closed loop. When used in a microgravity environment, a separate propulsion system is generally needed for safety and control, since there is no physical connection to a spacecraft. The portable life support system used in the Apollo lunar landing missions used lithium hydroxide to remove

140-401: A fire hydrant . The meters are normally made of aluminum to be lightweight, and are usually 7.5 cm (3 in) capacity. Water utilities often require them for measurement of water used in construction, pool filling, or where a permanent meter is not yet installed. The Woltman meter (invented by Reinhard Woltman in the 19th century) comprises a rotor with helical blades inserted axially in

210-456: A 279 watt-hour battery. For the extended missions of Apollo 15 through 17, the EVA stay time was doubled to 8 hours by increasing oxygen to 1,430 pounds per square inch (9.9 MPa), lithium hydroxide to 3.12 pounds (1.42 kg), cooling water to 11.5 pounds (5.2 liters), and battery capacity to 390 watt-hours. An emergency backup was provided in case the main system failed, by a separate unit called

280-750: A conditioning device as well as a differential pressure producer. Upstream requirements are between 0–5 diameters compared to up to 44 diameters for an orifice plate or 22 diameters for a Venturi. Because cone meters are generally of welded construction, it is recommended they are always calibrated prior to service. Inevitably heat effects of welding cause distortions and other effects that prevent tabular data on discharge coefficients with respect to line size, beta ratio and operating Reynolds numbers from being collected and published. Calibrated cone meters have an uncertainty up to ±0.5%. Un-calibrated cone meters have an uncertainty of ±5.0% Linear resistance meters, also called laminar flowmeters, measure very low flows at which

350-509: A helical screw. Because they are used for domestic water measurement, piston meters, also known as rotary piston or semi-positive displacement meters, are the most common flow measurement devices in the UK and are used for almost all meter sizes up to and including 40 mm ( 1 + 1 ⁄ 2  in). The piston meter operates on the principle of a piston rotating within a chamber of known volume. For each rotation, an amount of water passes through

420-424: A highly repeatable measurement over the life of the product. Because distance between the two laser sheets does not change, optical flowmeters do not require periodic calibration after their initial commissioning. Optical flowmeters require only one installation point, instead of the two installation points typically required by other types of meters. A single installation point is simpler, requires less maintenance and

490-459: A large penstock such as used at a hydroelectric power plant can be measured by averaging the flow velocity over the entire area. Propeller-type current meters (similar to the purely mechanical Ekman current meter , but now with electronic data acquisition) can be traversed over the area of the penstock and velocities averaged to calculate total flow. This may be on the order of hundreds of cubic meters per second. The flow must be kept steady during

560-402: A long porous plug; such low flows create small pressure differentials but longer flow elements create higher, more easily measured differentials. These flowmeters are particularly sensitive to temperature changes affecting the fluid viscosity and the diameter of the flow element, as can be seen in the governing Hagen–Poiseuille equation . A "variable area meter" measures fluid flow by allowing

630-405: A maximum of about 30 minutes of emergency oxygen for breathing and cooling. This could be extended to 75 to 90 minutes with a "buddy system" hose that used the other astronaut's functional PLSS for cooling (only). This allowed the vent valve to be partly closed to decrease the oxygen flow rate. The PLSS was 26 inches (66 cm) high, 18 inches (46 cm) wide, and 10 inches (25 cm) deep. It

700-460: A newer differential pressure metering device first launched in 1985 by McCrometer in Hemet, CA. The cone meter is a generic yet robust differential pressure (DP) meter that has shown to be resistant to effects of asymmetric and swirling flow. While working with the same basic principles as Venturi and orifice type DP meters, cone meters don't require the same upstream and downstream piping. The cone acts as

770-526: A particle crosses the first beam. The detecting optics collects scattered light on a photodetector, which then generates a pulse signal. As the same particle crosses the second beam, the detecting optics collect scattered light on a second photodetector, which converts the incoming light into a second electrical pulse. By measuring the time interval between these pulses, the gas velocity is calculated as V = D / t {\displaystyle V=D/t} where D {\displaystyle D}

SECTION 10

#1732858555194

840-464: A rotary separator. The removed water is stored and used to supplement the water supply used in the LCVG. The sublimator also cools the remaining oxygen to about 55 °F (13 °C). A flow sensor monitors the flow rate. Extra oxygen is added to the flow from a storage tank as necessary, downstream of the flow sensor. The oxygen is then returned to the suit at the back of the head, where it flows down over

910-409: Is a device inserted into the flowing fluid that produces a physical property that can be accurately related to flow. For example, an orifice plate produces a pressure drop that is a function of the square of the volume rate of flow through the orifice. A vortex meter primary flow element produces a series of oscillations of pressure. Generally, the physical property generated by the primary flow element

980-468: Is a shortened version of a Venturi meter, with a lower pressure drop than an orifice plate. As with these flowmeters the flow rate in a Dall tube is determined by measuring the pressure drop caused by restriction in the conduit. The pressure differential is typically measured using diaphragm pressure transducers with digital readout. Since these meters have significantly lower permanent pressure losses than orifice meters, Dall tubes are widely used for measuring

1050-414: Is a variable area orifice, where a spring-loaded tapered plunger is deflected by flow through an orifice. The displacement can be related to the flow rate. Optical flowmeters use light to determine flow rate. Small particles which accompany natural and industrial gases pass through two laser beams focused a short distance apart in the flow path in a pipe by illuminating optics. Laser light is scattered when

1120-428: Is a velocity type meter which has an impeller which rotates horizontally on a vertical shaft. The impeller element is in a housing in which multiple inlet ports direct the fluid flow at the impeller causing it to rotate in a specific direction in proportion to the flow velocity. This meter works mechanically much like a single jet meter except that the ports direct the flow at the impeller equally from several points around

1190-455: Is designed to record instantaneous velocity components at a single point with a relatively high frequency. Measurements are performed by measuring the velocity of particles in a remote sampling volume based upon the Doppler shift effect. Thermal mass flowmeters generally use combinations of heated elements and temperature sensors to measure the difference between static and flowing heat transfer to

1260-401: Is forced out of the meter as the gear teeth mesh and reduce the available pockets to nearly zero volume. Helical gear flowmeters get their name from the shape of their gears or rotors. These rotors resemble the shape of a helix, which is a spiral-shaped structure. As the fluid flows through the meter, it enters the compartments in the rotors, causing the rotors to rotate. The length of the rotor

1330-425: Is indicated by a gearing and register arrangement, which is connected to the disk. It is reliable for flow measurements within 1 percent. The turbine flowmeter (better described as an axial turbine) translates the mechanical action of the turbine rotating in the liquid flow around an axis into a user-readable rate of flow (gpm, lpm, etc.). The turbine tends to have all the flow traveling around it. The turbine wheel

1400-404: Is less prone to errors. Commercially available optical flowmeters are capable of measuring flow from 0.1 m/s to faster than 100 m/s (1000:1 turn down ratio) and have been demonstrated to be effective for the measurement of flare gases from oil wells and refineries, a contributor to atmospheric pollution. Open channel flow describes cases where flowing liquid has a top surface open to

1470-439: Is more convenient to measure than the flow itself. The properties of the primary flow element, and the fidelity of the practical installation to the assumptions made in calibration, are critical factors in the accuracy of the flow measurement. A positive displacement meter may be compared to a bucket and a stopwatch. The stopwatch is started when the flow starts and stopped when the bucket reaches its limit. The volume divided by

SECTION 20

#1732858555194

1540-679: Is not equivalent to the same gas under different conditions. References will be made to "actual" flow rate through a meter and "standard" or "base" flow rate through a meter with units such as acm/h (actual cubic meters per hour), sm /sec (standard cubic meters per second), kscm/h (thousand standard cubic meters per hour), LFM (linear feet per minute), or MMSCFD (million standard cubic feet per day). Gas mass flow rate can be directly measured, independent of pressure and temperature effects, with ultrasonic flow meters , thermal mass flowmeters , Coriolis mass flowmeters , or mass flow controllers . For liquids, various units are used depending upon

1610-423: Is set in the path of a fluid stream. The flowing fluid impinges on the turbine blades, imparting a force to the blade surface and setting the rotor in motion. When a steady rotation speed has been reached, the speed is proportional to fluid velocity. Turbine flowmeters are used for the measurement of natural gas and liquid flow. Turbine meters are less accurate than displacement and jet meters at low flow rates, but

1680-515: Is sufficient that the inlet and outlet are always separated from each other thus blocking a free flow of liquid. The mating helical rotors create a progressive cavity which opens to admit fluid, seals itself off and then opens up to the downstream side to release the fluid. This happens in a continuous fashion and the flowrate is calculated from the speed of rotation. This is the most commonly used measurement system for measuring water supply in houses. The fluid, most commonly water, enters in one side of

1750-477: Is the Thorpe tube flowmeter . Floats are made in many different shapes, with spheres and spherical ellipses being the most common. Some are designed to spin visibly in the fluid stream to aid the user in determining whether the float is stuck or not. Rotameters are available for a wide range of liquids but are most commonly used with water or air. They can be made to reliably measure flow down to 1% accuracy. Another type

1820-614: Is the distance between the laser beams and t {\displaystyle t} is the time interval. Laser-based optical flowmeters measure the actual speed of particles, a property which is not dependent on thermal conductivity of gases, variations in gas flow or composition of gases. The operating principle enables optical laser technology to deliver highly accurate flow data, even in challenging environments which may include high temperature, low flow rates, high pressure, high humidity, pipe vibration and acoustic noise. Optical flowmeters are very stable with no moving parts and deliver

1890-457: Is the flow rate, K {\displaystyle K} is a constant, H {\displaystyle H} is the water level, and X {\displaystyle X} is an exponent which varies with the device used; or it is converted according to empirically derived level/flow data points (a "flow curve"). The flow rate can then be integrated over time into volumetric flow. Level to flow devices are commonly used to measure

1960-417: Is the quantification of bulk fluid movement. Flow can be measured using devices called flowmeters in various ways. The common types of flowmeters with industrial applications are listed below: Flow measurement methods other than positive-displacement flowmeters rely on forces produced by the flowing stream as it overcomes a known constriction, to indirectly calculate flow. Flow may be measured by measuring

2030-400: Is the volumetric flow rate multiplied by the energy content per unit volume or mass flow rate multiplied by the energy content per unit mass. Energy flow rate is usually derived from mass or volumetric flow rate by the use of a flow computer . In engineering contexts, the volumetric flow rate is usually given the symbol Q {\displaystyle Q} , and the mass flow rate,

2100-729: The Earth weight of 3.1 kg) on the Moon). Similar systems have been used by Space Shuttle astronauts, and are currently used by International Space Station crews. The primary life support system for the EMU suit used on the Space Shuttle and International Space Station is manufactured by Hamilton Sundstrand . It is mounted to the back of the Hard Upper Torso (HUT) assembly. Oxygen (O 2 ), carbon dioxide (CO 2 ) and water vapor are drawn from

2170-558: The Oxygen Purge System (OPS), mounted on top of the PLSS, immediately behind the astronaut's helmet. The OPS maintained suit pressure and removed carbon dioxide, heat and water vapor through a continuous, one-way air flow vented to space. When activated, the OPS provided oxygen to a separate inlet on the pressure suit, once a vent valve on a separate suit outlet was manually opened. The OPS provided

Primary life support system - Misplaced Pages Continue

2240-408: The air; the cross-section of the flow is only determined by the shape of the channel on the lower side, and is variable depending on the depth of liquid in the channel. Techniques appropriate for a fixed cross-section of flow in a pipe are not useful in open channels. Measuring flow in waterways is an important open-channel flow application; such installations are known as stream gauges . The level of

2310-426: The application and industry, but might include gallons (U.S. or imperial) per minute, liters per second, liters per m per hour, bushels per minute or, when describing river flows, cumecs (cubic meters per second) or acre-feet per day. In oceanography a common unit to measure volume transport (volume of water transported by a current for example) is a sverdrup (Sv) equivalent to 10  m /s. A primary flow element

2380-475: The astronaut's face. By delivering oxygen to the helmet and drawing gas from the extremities, the suit is designed to ensure that the suit occupant breathes the freshest possible oxygen. The operating pressure of the space suit is maintained at 4.3  psi (30  kPa ) (0.3 atm ~ one third of Earth atmospheric pressure ) during extravehicular operations , and 0.7 psi (4.8 kPa) relative to external pressure while in intravehicular mode ( i.e. , inside

2450-454: The carbon dioxide from the breathing air, and circulated water in an open loop through a liquid-cooled garment , expelling the water into space, where it turned to ice crystals. Some of the water was also used to remove excess heat from the astronaut's breathing air, and collected for dumping into the spacecraft 's wastewater tank after an EVA. The PLSS also contained a radio transceiver and antenna for communications, which were relayed through

2520-445: The channel and measure the velocity from above and then use ultrasound to measure the depth of the water from above. Radar devices can only measure surface velocities, whereas laser-based devices can measure velocities sub-surface. A known amount of dye (or salt ) per unit time is added to a flow stream. After complete mixing, the concentration is measured. The dilution rate equals the flow rate. Acoustic Doppler velocimetry (ADV)

2590-526: The circumference of the element, not just one point; this minimizes uneven wear on the impeller and its shaft. Thus these types of meters are recommended to be installed horizontally with its roller index pointing skywards. The Pelton wheel turbine (better described as a radial turbine ) translates the mechanical action of the Pelton wheel rotating in the liquid flow around an axis into a user-readable rate of flow (gpm, lpm, etc.). The Pelton wheel tends to have all

2660-441: The cross sectional area of the device to vary in response to the flow, causing some measurable effect that indicates the rate. A rotameter is an example of a variable area meter, where a weighted "float" rises in a tapered tube as the flow rate increases; the float stops rising when area between float and tube is large enough that the weight of the float is balanced by the drag of fluid flow. A kind of rotameter used for medical gases

2730-486: The cross-sectional area yields a flow rate which can be integrated into volumetric flow. There are two types of area velocity flowmeter: (1) wetted; and (2) non-contact. Wetted area velocity sensors have to be typically mounted on the bottom of a channel or river and use Doppler to measure the velocity of the entrained particles. With depth and a programmed cross-section this can then provide discharge flow measurement. Non-contact devices that use laser or radar are mounted above

2800-411: The extremities of the suit by the liquid cooling and ventilation garment or LCVG , which sends the gas to the PLSS. When gas enters the PLSS, activated charcoal removes odors and lithium hydroxide (LiOH) removes carbon dioxide. Next, the gas passes through a fan which maintains a flow rate of about six cubic feet per minute. A sublimator then condenses water vapor, which is removed by a "slurper" and

2870-447: The flow of surface waters (springs, streams, and rivers), industrial discharges, and sewage. Of these, weirs are used on flow streams with low solids (typically surface waters), while flumes are used on flows containing low or high solids contents. The cross-sectional area of the flow is calculated from a depth measurement and the average velocity of the flow is measured directly (Doppler and propeller methods are common). Velocity times

Primary life support system - Misplaced Pages Continue

2940-663: The flow profile and fluid conditions. Turbine flowmeters are commonly best suited for low viscosity, as large particulate can damage the rotor. When choosing a meter for an application that requires particulate flowing through the pipe, it is best to use a meter without moving parts such as a Magnetic flowmeters . Fire meters are a specialized type of turbine meter with approvals for the high flow rates required in fire protection systems. They are often approved by Underwriters Laboratories (UL) or Factory Mutual (FM) or similar authorities for use in fire protection. Portable turbine meters may be temporarily installed to measure water used from

3010-421: The flow rate of large pipeworks. Differential pressure produced by a Dall tube is higher than Venturi tube and nozzle, all of them having same throat diameters. A pitot tube is used to measure fluid flow velocity. The tube is pointed into the flow and the difference between the stagnation pressure at the tip of the probe and the static pressure at its side is measured, yielding the dynamic pressure from which

3080-412: The flow the higher the frequency and the voltage output. The paddle wheel meter is designed to be inserted into a pipe fitting, either 'in-line' or insertion style. These are available with wide range of fittings styles, connection methods and materials such as PVDF, polypropylene, and stainless steel. Similar to turbine meters, the paddle wheel meter require a minimum run of straight pipe before and after

3150-416: The flow traveling around it with the inlet flow focused on the blades by a jet. The original Pelton wheels were used for the generation of power and consisted of a radial flow turbine with "reaction cups" which not only move with the force of the water on the face but return the flow in opposite direction using this change of fluid direction to further increase the efficiency of the turbine . Flow through

3220-467: The flow, much like a ducted fan; it can be considered a type of turbine flowmeter. They are commonly referred to as helix meters, and are popular at larger sizes. A single jet meter consists of a simple impeller with radial vanes, impinged upon by a single jet. They are increasing in popularity in the UK at larger sizes and are commonplace in the EU . Paddle wheel flowmeters consist of three primary components:

3290-413: The fluid velocity is calculated using Bernoulli's equation . A volumetric rate of flow may be determined by measuring the velocity at different points in the flow and generating the velocity profile. Averaging pitot tubes (also called impact probes) extend the theory of pitot tube to more than one dimension. A typical averaging pitot tube consists of three or more holes (depending on the type of probe) on

3360-444: The material's density . The density of a liquid is almost independent of conditions. This is not the case for gases, the densities of which depend greatly upon pressure, temperature and to a lesser extent, composition. When gases or liquids are transferred for their energy content, as in the sale of natural gas , the flow rate may also be expressed in terms of energy flow, such as gigajoule per hour or BTU per day. The energy flow rate

3430-418: The measured differential pressure is linearly proportional to the flow and to the fluid viscosity. Such flow is called viscous drag flow or laminar flow, as opposed to the turbulent flow measured by orifice plates, Venturis and other meters mentioned in this section, and is characterized by Reynolds numbers below 2000. The primary flow element may consist of a single long capillary tube, a bundle of such tubes, or

3500-421: The measuring element does not occupy or severely restrict the entire path of flow. The flow direction is generally straight through the meter, allowing for higher flow rates and less pressure loss than displacement-type meters. They are the meter of choice for large commercial users, fire protection, and as master meters for the water distribution system . Strainers are generally required to be installed in front of

3570-450: The measuring tip arranged in a specific pattern. More holes allow the instrument to measure the direction of the flow velocity in addition to its magnitude (after appropriate calibration). Three holes arranged in a line allow the pressure probes to measure the velocity vector in two dimensions. Introduction of more holes, e.g. five holes arranged in a "plus" formation, allow measurement of the three-dimensional velocity vector. Cone meters are

SECTION 50

#1732858555194

3640-405: The meter and strikes the nutating disk, which is eccentrically mounted. The disk must then "wobble" or nutate about the vertical axis, since the bottom and the top of the disk remain in contact with the mounting chamber. A partition separates the inlet and outlet chambers. As the disk nutates, it gives direct indication of the volume of the liquid that has passed through the meter as volumetric flow

3710-476: The meter to protect the measuring element from gravel or other debris that could enter the water distribution system. Turbine meters are generally available for 4 to 30 cm ( 1 + 1 ⁄ 2 –12 in) or higher pipe sizes. Turbine meter bodies are commonly made of stainless steel, bronze, cast Iron, or ductile iron. Internal turbine elements can be plastic or non-corrosive metal alloys. They are accurate in normal working conditions but are greatly affected by

3780-521: The outlet port. Meanwhile, fluid entering the inlet port will be driven into the measurement chamber of side A, which is now open. The teeth on side B will now close off the fluid from entering side B. This cycle continues as the gears rotate and fluid is metered through alternating measurement chambers. Permanent magnets in the rotating gears can transmit a signal to an electric reed switch or current transducer for flow measurement. Though claims for high performance are made, they are generally not as precise as

3850-415: The paddle wheel sensor, the pipe fitting and the display/controller. The paddle wheel sensor consists of a freely rotating wheel/impeller with embedded magnets which are perpendicular to the flow and will rotate when inserted in the flowing medium. As the magnets in the blades spin past the sensor, the paddle wheel meter generates a frequency and voltage signal which is proportional to the flow rate. The faster

3920-412: The piston chamber. Through a gear mechanism and, sometimes, a magnetic drive, a needle dial and odometer type display are advanced. An oval gear meter is a positive displacement meter that uses two or more oblong gears configured to rotate at right angles to one another, forming a T shape. Such a meter has two sides, which can be called A and B. No fluid passes through the center of the meter, where

3990-697: The pressure loss of fluids as they pass that constriction, or by measuring static and stagnation pressures to derive the dynamic pressure . A Venturi meter constricts the flow in some fashion, and pressure sensors measure the differential pressure before and within the constriction. This method is widely used to measure flow rate in the transmission of gas through pipelines , and has been used since Roman Empire times. The coefficient of discharge of Venturi meter ranges from 0.93 to 0.97. The first large-scale Venturi meters to measure liquid flows were developed by Clemens Herschel , who used them to measure small and large flows of water and wastewater beginning at

4060-403: The pressurized spacecraft). Technologies being considered for application in future PLSSs include pressure swing adsorption (PSA), a process by which CO 2 can be separated from gas more efficiently, and through a repeatable process, as opposed to the current LiOH canisters, which become saturated with each use, and are limited to around eight hours. By regenenerating the sorbent during EVA,

4130-497: The sensor. Flow displays and controllers are used to receive the signal from the paddle wheel meter and convert it into actual flow rate or total flow values. The processed signal can be used to control the process, generate an alarm, send signals to external etc. Paddle wheel flowmeters (also known as Pelton wheel sensors) offer a relatively low cost, high accuracy option for many flow system applications, typically with water or water-like fluids. A multiple jet or multijet meter

4200-568: The size and weight of the sorbent canister can be greatly reduced. PSA accomplishes this by venting CO 2 and water vapor into space. Rebreather Too Many Requests If you report this error to the Wikimedia System Administrators, please include the details below. Request from 172.68.168.132 via cp1112 cp1112, Varnish XID 389097649 Upstream caches: cp1112 int Error: 429, Too Many Requests at Fri, 29 Nov 2024 05:35:55 GMT Flow measurement Flow measurement

4270-426: The sliding vane design. Gear meters differ from oval gear meters in that the measurement chambers are made up of the gaps between the teeth of the gears. These openings divide up the fluid stream and as the gears rotate away from the inlet port, the meter's inner wall closes off the chamber to hold the fixed amount of fluid. The outlet port is located in the area where the gears are coming back together. The fluid

SECTION 60

#1732858555194

4340-571: The spacecraft's communication system to Earth. PLSS controls were provided in the Remote Control Unit (RCU) mounted on the astronaut's chest. Oxygen and water were rechargeable for multiple EVAs from the spacecraft's environmental control system. Lunar surface EVA times for the first four missions (Apollo 11 through 14) were limited to 4 hours, with oxygen stored at 1,020 pounds per square inch (7.0 MPa), 3.0 pounds (1.4 kg) of lithium hydroxide, 8.5 pounds (3.9 liters) of cooling water, and

4410-505: The symbol m ˙ {\displaystyle {\dot {m}}} . For a fluid having density ρ {\displaystyle \rho } , mass and volumetric flow rates may be related by m ˙ = ρ Q {\displaystyle {\dot {m}}=\rho Q} . Gases are compressible and change volume when placed under pressure, are heated or are cooled. A volume of gas under one set of pressure and temperature conditions

4480-429: The teeth of the two gears always mesh. On one side of the meter (A), the teeth of the gears close off the fluid flow because the elongated gear on side A is protruding into the measurement chamber, while on the other side of the meter (B), a cavity holds a fixed volume of fluid in a measurement chamber. As the fluid pushes the gears, it rotates them, allowing the fluid in the measurement chamber on side B to be released into

4550-420: The time gives the flow rate. For continuous measurements, we need a system of continually filling and emptying buckets to divide the flow without letting it out of the pipe. These continuously forming and collapsing volumetric displacements may take the form of pistons reciprocating in cylinders, gear teeth mating against the internal wall of a meter or through a progressive cavity created by rotating oval gears or

4620-486: The traverse of the current meters. Methods for testing hydroelectric turbines are given in IEC standard 41. Such flow measurements are often commercially important when testing the efficiency of large turbines. There are several types of flowmeter that rely on Bernoulli's principle . The pressure is measured either by using laminar plates, an orifice, a nozzle, or a Venturi tube to create an artificial constriction and then measure

4690-429: The velocity of fluid over a known area. For very large flows, tracer methods may be used to deduce the flow rate from the change in concentration of a dye or radioisotope. Both gas and liquid flow can be measured in physical quantities of kind volumetric flow rate or mass flow rates , with respective SI units such as cubic meters per second or kilograms per second, respectively. These measurements are related by

4760-402: The very end of the 19th century. An orifice plate is a plate with a hole through it, placed perpendicular to the flow; it constricts the flow, and measuring the pressure differential across the constriction gives the flow rate. It is basically a crude form of Venturi meter , but with higher energy losses. There are three type of orifice: concentric, eccentric, and segmental. The Dall tube

4830-391: The water is measured at a designated point behind weir or in flume using various secondary devices (bubblers, ultrasonic, float, and differential pressure are common methods). This depth is converted to a flow rate according to a theoretical formula of the form Q = K H X {\displaystyle Q=KH^{X}} where Q {\displaystyle Q}

4900-585: Was tested at the Houston Flight Center by James P. Lucas, working for Hamilton Standard , and by various astronauts in neutral buoyancy tanks at Dallas. It was tested in space for the first time by Rusty Schweickart in a stand-up EVA in Earth orbit on Apollo 9 . His PLSS weighed 84 pounds (38 kg) on Earth, but only 14 lb (equivalent to the Earth weight of 6.4 kg) on the Moon. The OPS weighed 41 pounds (19 kg) on Earth (6.8 lb (equivalent to

#193806