Methods and apparatus for monitoring a filter bed by differential pressure

A filter bed for a liquid filtration system, comprising:

• (a) a layer of support gravel;
• (b) at least one layer of filter media situated on top of said layer of support gravel;
• (c) a controller located outside the filter bed to determine pressure differentials from a plurality of pressure readings;
• and,
• (d) a differential pressure monitor located within the filter bed for measuring pressure at a plurality of heights in the filter bed, the monitor comprising:
• a body having an upper end and a lower end;
• a plurality of pressure sensors located on said body for obtaining pressure readings at a plurality of corresponding heights across said at least one layer of filter media wherein the monitor is at least partially submerged in the filter media;
• and,
• a transmitter to transmit the pressure readings from said pressure sensor to said controller, wherein no part of said controller or said monitor passes through walls of the liquid filtration system.

A differential pressure monitor for measuring the pressure at a plurality of heights in a filter bed, the monitor comprising:

• (a) a body having an upper end, a lower end, and at least one sidewall, said body having a generally uniform cross section;
• (b) a plurality of pressure sensors located on the elongated body for obtaining pressure readings of pressures across the filter bed at a plurality of corresponding heights across a plurality of layers of filter media wherein the monitor is at least partially submerged in the filter media;
• and,
• (c) a controller operable to determine at least one differential pressure, the differential pressure being the difference in the pressure across the filter bed between pressures measured by at least two of the sensors at different heights within the filter bed.

A method of measuring at least one diagnostic reading at at least one location in a filter bed in a liquid filtration system, the filter bed having at least one layer of filter media and an upper surface at the top of the layer of filter media, the method comprising the steps of:

• (a) providing a monitor comprising:
• a body having an upper end and a lower end;
• at least one sensor located on said body to obtain at least one diagnostic reading at at least one location in the filter bed;
• (b) placing the monitor in the filter bed by positioning the monitor down through the upper surface of the filter bed and into the filter media;
• and,
• (c) measuring at least one diagnostic reading at at least one location within the filter media in the filter bed with the monitor.

A method of measuring of least one pressure reading at at least one location in a filter bed in a liquid filtration system, the filter bed having at least one layer of filter media and an upper surface at the top of the layer of filter media, the method comprising the steps of:

• (a) providing a differential pressure monitor comprising:
• a body having an upper end and a lower end;
• at least one pressure sensor located on said body for obtaining at least one pressure reading at at least one location in the filter bed;
• (b) placing the differential pressure monitor in the filter bed by positioning the monitor down through the upper surface of the filter bed and into the filter media;
• and,
• (c) measuring at least one pressure reading at at least one location within the filter media in the filter bed with the differential pressure monitor.

A method of monitoring and controlling performance of a filter bed in a liquid filtration system during filtration to achieve more efficient backwashing and filtration operation, the filter bed having two layers of filter media and an upper surface at the top of an upper layer of the two layers of filter media, the method comprising the steps of:

• (a) providing a controller to determine a pressure differential from a plurality of pressure readings;
• (b) providing a differential pressure monitor comprising:
• a body having an upper end and a lower end;
• three pressure sensors for obtaining pressure readings at three corresponding locations during filtration, the three locations being:
• (1) at a distance adjacent to and vertically above the upper layer of filter media in the liquid filtration system so as to measure the pressure at the upper surface of the upper layer of filter media, the pressure being p1;
• (2) at an interface of the upper layer of filter media and a lower layer of the two layers of filter media, the pressure being p2;
• and,
• (3) at a point proximate a bottom surface of the lower layer of filter media, the pressure being p3;
• and
• a transmitter to transmit the pressure readings from the pressure sensors to the controller, wherein the differential pressure is the difference in the pressure between pressures measured at two different heights;
• (c) starting filtration by introducing influent to the liquid filtration system at a location vertically above the upper surface of the upper layer of filter media;
• (d) monitoring pressure readings p1, p2, and p3 at periodic intervals and recording such measurements on the controller to obtain a characteristic profile of the filter bed during filtration, wherein no part of the controller or the monitor passes through a wall of the liquid filtration system.

A method of monitoring and controlling performance of a filter bed in a liquid filtration system during backwashing to achieve more efficient backwashing and filtration operation, the filter bed having two layers of filter media, an upper surface at an upper layer of filter media, a lower surface at a lower layer of filter media, and a bottom surface, the method comprising the steps of:

• (a) providing a controller to determine a pressure differential from a plurality of pressure readings;
• (b) providing a differential pressure monitor comprising:
• a body having an upper end and a lower end;
• three pressure sensors for obtaining pressure readings at three corresponding locations during backwashing, the three locations being;
• (1) at a distance adjacent to and vertically above the upper layer of filter media so as to measure the pressure at the upper surface of the upper layer of filter media, the pressure being p1;
• (2) at an interface of the upper layer of filter media and the lower layer of filter media, the pressure being p2;
• and,
• (3) at a point proximate the lower surface of the lower layer of filter media, the pressure being p3;
• and, a
• transmitter to transmit the pressure readings from the pressure sensors to the controller, wherein the differential pressure is the difference in pressure between pressures measured at two different heights;
• (c) pumping water in an upward direction in through the bottom surface of the filter bed and through the filter bed at a relatively slow rate of flow;
• (d) gradually increasing the rate of flow of water being pumped into the liquid filtration system;
• (e) periodically measuring pressure readings p1, p2 and p3;
• (f) recording the pressure readings on the controller to obtain a characteristic profile of the filter bed during backwashing;
• and,
• (g) monitoring differential pressure p3-p1 to determine a backwash differential pressure and when it approaches a constant value, starting backwashing at the rate of water flow being pumped into the liquid filtration system to achieve the backwash differential pressure.

A method of measuring at least one turbidity reading at at least one location in a filter bed in a liquid filtration system, the filter bed having at least one layer of filter media and an upper surface at the top of the layer of filter media, the method comprising the steps of:

• (a) providing a turbidity monitor comprising:
• a body having an upper end and a lower end;
• at least one turbidity sensor located on said body for obtaining at least one turbidity reading at at least one location in the filter bed;
• (b) placing the turbidity monitor in the filter bed through the top of the liquid filtration system and into the filter media such that the monitor may be removed through the upper surface of the filter bed;
• and,
• (c) measuring at least one turbidity reading at at least one location within the filter media in the filter bed.

A method of obtaining at least one water sample at at least one location in a filter bed in a liquid filtration system, the filter bed having at least one layer of filter media and an upper surface at the top of the layer of filter media, the method comprising the steps of:

• (a) providing a water sampling device comprising:
• a body having an upper end and a lower end;
• at least one path of fluid communication between the filter bed and the inner cavity;
• a pump for creating suction to draw water out of the filter bed through the at least one path;
• (b) placing the device at a location within the filter media in the filter bed by placing the device through the top of the liquid filtration system such that the monitor may be removed through the upper surface of the filter bed;
• and,;
• (c) drawing at least one water sample out of the filter media within the filter bed, into said body, and out of the filter media within the filter bed.

A method of monitoring and controlling at least one condition of a filter bed in a liquid filtration system, the filter bed having at least one layer of filter media, the method comprising the steps of:

• (a) providing a monitor for monitoring at least one condition of the filter bed;
• (b) backwashing the filter bed;
• and,
• (c) inserting the monitor into the filter media during the step of backwashing.