A self-correcting pressure-based mass flow control apparatus includes outlet pressure sensing to enable correction for non-ideal operating conditions. Further the mass flow control apparatus having a fluid pathway, a shutoff valve in the fluid pathway, a reference volume in the fluid pathway, a first pressure measuring sensor in fluid communication with the reference volume, a first temperature measuring sensor providing a temperature signal indicative of the fluid temperature within the reference volume, a proportional valve in the fluid pathway, and a second pressure measuring sensor in fluid communication with the fluid pathway.

A system comprises a flow restrictor connected to a fluid flow path and located upstream from a chamber. The flow restrictor comprises an adjustable flow restriction aperture defined by the flow path region between a first element and a second element of the flow restrictor, and a drive unit configured to adjust the relative positions of the first element, second element or both to modify the fluid flow path across the aperture. The first or second element provides a curved boundary in the aperture flow path to form a converging region, a region of closest approach and a diverging region, within the flow path. Flow rate may be determined using a reference volume upstream from the flow restrictor.

An improved fluid level verification apparatus with an integral, internal source of illumination that is powered by an integral, internal energy source and is activated by a motion sensor or any other sensor commonly known in the art to detect the presence of a person in dark or dimly lit environments. The preferred light source is a light emitting diode (LED). A second embodiment of the integral, internal source of illumination that is powered by an integral, internal energy source and is activated by a motion sensor or any other sensor commonly known in the art to detect the presence of a person in dark or dimly lit environments is applied to a fluid reservoir tank.

Disclosed are mass flow controllers, apparatuses for manufacturing semiconductor devices, and methods of maintenance thereof. The mass flow controller may control an amount of a gas provided into a chamber. The mass flow controller may be configured to obtain an absolute volume of the gas provided into the chamber at a standard flow rate when the mass flow controller is initially used. The mass flow controller may be configured to obtain a detected flow rate of the gas provided at a measured flow rate after the mass flow controller has been used for a predetermined time. The mass flow controller may be configured to compare the detected flow rate and the standard flow rate to verify a full-scale error in the measured flow rate.

A method of measuring airflow from an HVAC outlet vent using a volume fill airflow measurement device having a LIDAR or Time-of-Flight (ToF) laser-ranging sensor to detect a filled state of a volume capture element or bag, comprising placing a frame having the bag sealably attached thereto over the vent to be measured, starting a timer, stopping the timer automatically in response to the LIDAR or Time-of-Flight (ToF) laser-ranging sensor measuring the distance to be within a predetermined range, and calculating the measured airflow based on the volume of the bag and the time for the airflow to fill the bag. The measured airflow is then displayed on the device display.

An automated liquid inventory monitoring and inventory reconciliation system. The system uses a liquid densitometer to precisely measure the density of liquid being dispensed. This allows the system to account for the significant temperature-induced volume variations existing in common liquids such as gasoline. In the preferred embodiments, a fuel inventory processor tracks the quantity of fuel loaded into the tank and the quantity of fuel dispensed to maintain an ongoing computation of the quantity of fuel that should be present in the tank. An accurate tank depth measurement device is also employed. The processor compares the tank depth measurement to the computed quantity of fuel in the tank and uses the values to create an updated tank strapping chart.

Fluid level measurements for the shared tank and outflow information provided by calibrated flow meters corresponding to dispensing stations connected to the shared tank may be used to derive a filled volume model for the tank as a function of fluid level. Subsequently, a filled volume change for a shared tank over a selected time interval may be determined from pre-change and post-change fluid level measurements. The change in filled volume may be compared with the total fluid flow over the selected time interval as indicated by the flow meters of active dispensing stations. If the filled volume change for the tank is substantially different than the total fluid flow indicated by the flow meters, the flow meters may be collectively adjusted to provide a more accurate indication of the filled volume change in the shared tank.

A method includes determining a rotational position of a crankshaft in a multiplex pump from one or more sensors disposed on the crankshaft, determining a position of each of a plurality of pistons along a corresponding pump bore in relation to a total stroke length of each piston and a connecting rod length, calculating an individual theoretical displaced volume of fluid for each of the pump bores in the multiplex pump based on the rotational position of the crankshaft, and summing the individual theoretical displaced volumes to determine a total theoretical pumped volume by the multiplex pump. A calibration method includes determination of the multiplex pump efficiency versus speed and discharge pressure, and the effect of pump leakage and valve closing delay on the pump efficiency. Verification of the pump performance and efficiency may be controlled during pumping to insure the validity of the last calibration data set.

A closed loop system for the calibration of a multiphase meter, such as a multiphase flow meter or water cut meter, and a method of employing the system in calibration of multiphase meters in crude oil production processes. The system includes an oil and water separation vessel, oil and water flow meters, valves, pumps, and a single phase calibration unit. The system employs a two-step calibration process. First internal single phase oil and water meters are calibrated using the single phase calibration unit; subsequently multiphase meter calibration is achieved using the two precalibrated single phase flow meters.

Mass flow control systems and methods for controlling the mass flow rate of a gas through a primary conduit are disclosed. One mass flow control system includes a primary conduit for directing a flow of a gas and an adjustment system configured to divert a portion of the gas from the primary conduit to a secondary conduit and provide an adjustment signal that changes when a composition of the gas changes. A mass flow controller is operatively coupled to the primary conduit to control a primary flow rate of the gas. The mass flow controller includes a valve to control the primary flow rate of the gas and a control loop configured to receive the adjustment signal and control the valve to provide the primary flow rate of the gas at a set point.