# US 2014/0360058 A1 · Pump Apparatus and Underwater Trenching Apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0360058 A1 - Document ID: US20140360058A1 - Status: Published application - Kind: A1 - Application number: 14/366,114 - Filed: 2012-12-21 - Published: 2014-12-11 - Earliest claimed: 2011-12-22 - Assignees: IHC Engineering Business Limited - Applicants: Ihc Engineering Business Limited - Inventors: Jonathan Ralph Manchester - Web page: https://patentgrep.com/patent/US20140360058A1 ## CPC - E02F 5/107: {using blowing-effect devices, e.g. jets (digging devices using a blowing effect per se E02F3/9206)} - E02F 3/90: Component parts {, e.g. arrangement or adaptation of pumps} - E02F 3/9206: {Digging devices using blowing effect only, like jets or propellers (E02F5/107 takes precedence; passive suction heads with jets E02F3/925; active suction heads with jets E02F3/9262; drilling by jets E21B7/18; slitting by jets E21C25/60)} - E02F 9/226: {Safety arrangements, e.g. hydraulic driven fans, preventing cavitation, leakage, overheating} - F04B 23/14: at least one pump being of the non-positive-displacement type - F04D 13/12: Combinations of two or more pumps (combinations with priming pumps or booster pumps to counteract vapour-lock F04D9/04) - F04F 5/12: of multi-stage type - F04F 5/48: Control - F04F 5/54: Installations characterised by use of jet pumps, e.g. combinations of two or more jet pumps of different type - E02F: DREDGING; SOIL-SHIFTING (winning peat E21C49/00) - F04B: POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS (machines for liquids, or pumps, of rotary-piston or oscillating-piston type F04C; non-positive-displacement pumps F04D; pumping of fluid by direct contact of another fluid or by using inertia of fluid to be pumped F04F) - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - F04F: PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED {(evacuating by sorption F04B)}; SIPHONS {(conveying materials in bulk by flows of gas, liquid of foam B65G53/00)} ## Abstract A pump apparatus comprises a primary pump having a relatively low pressure fluid input and a relatively high pressure fluid output and means, associated with said primary pump fluid input, operable where the ambient pressure is insufficient substantially to prevent cavitation in the primary pump, to locally increase the pressure at said primary pump fluid input ## Claims ### Claim 1 A pump apparatus comprising a primary pump having a relatively low pressure fluid input and a relatively high pressure fluid output and means, associated with said primary pump fluid input, operable where the ambient pressure is insufficient substantially to prevent cavitation in the primary pump, to locally increase the pressure at said primary pump fluid input. ### Claim 2 (depends on 1) A pump apparatus as claimed in claim 1 wherein said means operable to locally increase the pressure at said fluid input is a jet pump. ### Claim 3 (depends on 2) A pump apparatus as claimed in claim 2 wherein the jet pump has an input and an output, the input being in fluid communication with the high pressure output of the primary pump and the output being in fluid communication with the input of the primary pump. ### Claim 4 (depends on 3) A pump apparatus as claimed in claim 3 further comprising an isolator operable to isolate the jet pump from the high pressure outlet of the primary pump. ### Claim 5 (depends on 1) A pump apparatus as claimed in claim 1 wherein the primary pump comprises one or more controllable flow restricting valves upstream of the high pressure fluid output, said valves having a flow restricting condition and a non-flow restricting condition, said flow restricting condition operatively reducing the input flow to the primary pump and increasing the exhaust pressure at the primary pump fluid output, as compared to the non-flow restricting condition. ### Claim 6 An underwater trenching apparatus for operation in shallow water, the apparatus comprising a trench-cutting high pressure jetting tool and a primary pump having a relatively high pressure fluid output in fluid communication with said jetting tool and a relatively low pressure fluid input, and means, associated with said primary pump fluid input, operable where the ambient pressure is insufficient to prevent cavitation in the primary pump, to locally increase the pressure at said primary pump fluid input. ### Claim 7 (depends on 6) An underwater trenching apparatus as claimed in claim 6 wherein said means operable to locally increase the pressure at said fluid input is a jet pump. ### Claim 8 (depends on 7) An underwater trenching apparatus claimed in claim 7 wherein the jet pump has an input and an output, the input being in fluid communication with the high pressure output of the primary pump and the output being in fluid communication with the input of the primary pump. ### Claim 9 (depends on 8) An underwater trenching apparatus as claimed in claim 8 further comprising an isolator operable to isolate the jet pump from the high pressure outlet of the primary pump, said isolator being operable where the ambient pressure is sufficient substantially to prevent cavitation in the primary pump. ### Claim 10 (depends on 6) An underwater trenching apparatus as claimed in claim 6 wherein the primary pump comprises one or more controllable flow restricting valves upstream of the high pressure fluid output, said valves having a flow restricting condition and a non-flow restricting condition, said flow restricting condition operatively reducing the input flow to the primary pump and increasing the exhaust pressure at the primary pump fluid output, as compared to the non-flow restricting condition. ### Claim 11 A method of operating an underwater trenching apparatus for operation in shallow water, the apparatus comprising a trench-cutting high pressure jetting tool and a primary pump having a relatively high pressure fluid output in fluid communication with said jetting tool and a relatively low pressure fluid input, the method comprising, where the ambient pressure is insufficient substantially to prevent cavitation in the primary pump, locally increasing the pressure at said primary pump fluid input. ### Claim 12 (depends on 11) A method as claimed in claim 11 comprising locally increasing the pressure at said fluid input using a jet pump in fluid communication with said fluid input. ### Claim 13 (depends on 12) A method as claimed in claim 12 wherein the jet pump has an input and an output, the input being in fluid communication with the high pressure output of the primary pump and the output being in fluid communication with the input of the primary pump. ### Claim 14 (depends on 13) A method as claimed in claim 13 further comprising isolating the jet pump from the high pressure outlet of the primary pump where the ambient pressure is sufficient substantially to prevent cavitation in the primary pump. ### Claim 15 (depends on 11) A method as claimed in claim 11 wherein the primary pump comprises one or more controllable flow restricting valves upstream of the high pressure fluid output, said valves having a flow restricting condition and a non-flow restricting condition, said flow restricting condition operatively reducing the input flow to the primary pump and increasing the exhaust pressure at the primary pump fluid output, as compared to the non-flow restricting condition, the method comprising, on initially starting the primary pump where the ambient pressure is insufficient substantially to prevent cavitation, causing the one or more flow restricting valves to adopt the flow restricting condition, and, when the pressure at the fluid input of the primary pump reaches a predetermined threshold value, causing the one or more flow restricting valves to adopt the non-flow restricting condition.