Disclosed is a sheath delivery system that uses a continuous flow of sheath fluid into a pressurized internal reservoir that substantially matches the outflow of sheath fluid through the nozzle of a flow cytometer. A substantially constant level of the sheath fluid is maintained. If the sheath fluid level falls below a desired level, or goes above a desired level, a dampened control system is used to reach the desired level. In addition, air pressure in the pressurized internal container is controlled so that an external sheath container can be removed and refilled with additional sheath fluid without stopping the sheath delivery system 100. Differences in pressure are detected by a droplet camera, which measures the droplet breakoff point to determine the pressure of the sheath fluid in the nozzle.

A water level detection system in a pool, spa, fountain or water feature, the water level detection system being provided with a tap line coupled to a plumbing line on a suction or supply side of a filtration system and admitting water from the pool, spa, fountain or water feature such that the change in level of the water in the tap line corresponds to a change in level of the water in the pool, spa, fountain or water feature. A sensing module has at least one sensor for detecting the height of a column of water or the pressure of a column of air in the water tap line. A controller is coupled to the sensing module and adapted to collect the data from the sensors that detect changes in the level of the water level of the pool, spa, fountain or water feature, communicate the detection of such a change, and report such a change to initiate addition or removal of water from the pool, spa, fountain or water feature body of water to adjust the water level in the body of water to a set point.

An evaporative media system having multiple media stages each served by a separate pump is disclosed. In one aspect, the evaporative media system has a first media stage and a second media stage. A first pump is provided that is configured to deliver water from the first compartment of the water storage tank to the first media stage. Additionally, a second pump is provided that is configured to deliver water from the first compartment of the water storage tank to the second media stage. Additional media stages and pumps may be provided as well. The disclosed configuration eliminates the need for individual staging valves, provides a higher level of operational redundancy, reduces electrical consumption, and can be provided at a lower cost, as compared to many existing systems.

Disclosed is a sheath delivery system that uses a continuous flow of sheath fluid into a pressurized internal reservoir that substantially matches the outflow of sheath fluid through the nozzle of a flow cytometer. A substantially constant level of the sheath fluid is maintained. If the sheath fluid level falls below a desired level, or goes above a desired level, a dampened control system is used to reach the desired level. In addition, air pressure in the pressurized internal container is controlled so that an external sheath container can be removed and refilled with additional sheath fluid without stopping the sheath delivery system 100. Differences in pressure are detected by a droplet camera, which measures the droplet breakoff point to determine the pressure of the sheath fluid in the nozzle.

A device for controlling flow of a fluid, comprising: a first valve comprising: a selectively openable inlet; an opening; a selectively openable outlet, arranged such that fluid may enter the first valve through the inlet, exit the first valve through the opening, enter the first valve through the opening and exit the first valve through the outlet; a first sensor for detecting a fluid; a second sensor for detecting a fluid, the first sensor and second sensor in fluid communication with the first valve via the opening; a controller for receiving signals from the first sensor and second sensor and for controlling opening and closing of the inlet and outlet in response to receiving said signals, arranged to allow, in use, a fluid to flow through the device by flowing: into the first valve through the inlet of the first valve; out of the first valve through the opening of the first valve; past the first sensor for detecting a fluid; to the second sensor for detecting a fluid; into the first valve through the opening of the first valve; out of the first valve through the outlet of the first valve.