Printer having recycling ink and pressure-equalized upstream and downstream ink lines

1. A printer comprising:

a printhead having an ink inlet and an ink outlet;

a pressure-regulating chamber containing ink at a predetermined first level relative to said printhead, said chamber comprising:

an inlet port;

an outlet port;

a return port positioned in a base of the chamber;

a float valve comprising:

(i) an arm pivotally mounted about a pivot;

(ii) a float mounted at one end of said arm; and

(iii) a valve stem attached to said arm, said valve stem having a valve head for closure of a valve seat, wherein said valve seat is positioned at the inlet port of said pressure-regulating chamber,

a snorkel extending from said return port and terminating at a snorkel outlet positioned above said first level of ink;

an air vent open to atmosphere, said air vent communicating with a headspace above said ink;

an upstream ink line interconnecting said outlet port and said ink inlet; and

a downstream ink line interconnecting said return port and said ink outlet,

said downstream ink line having a section looping below said first level of ink, wherein, in a printing configuration, a second level of ink in said snorkel is equal to said first level of ink in said chamber.

2. The printer of claim 1 , further comprising an ink reservoir in fluid communication with said inlet port.

3. The printer of claim 2 , wherein said float valve is biased towards a closed position by a positive ink pressure at said inlet port, said positive ink pressure being provided by said ink reservoir positioned above said chamber.

4. The printer of claim 1 , further comprising a printhead priming system.

5. The printer of claim 4 , wherein said priming system comprises an ink pump positioned in said downstream ink line.

6. The printer of claim 5 , wherein said pump is a peristaltic pump.

7. The printer of claim 4 , wherein, in a priming configuration, said pump pumps ink from said outlet port towards said return port so as to prime said printhead.

8. The printer of claim 5 , wherein said pump is a reversible pump.

9. The printer of claim 8 , wherein, in a de-priming configuration, said pump pumps ink from said return port towards said outlet port, so as to de-prime said printhead.

10. The printer of claim 8 , wherein said downstream ink line comprises inline filters positioned on either side of said pump.

11. The printer of claim 1 further comprising a first air accumulator communicating with said downstream ink line, said first air accumulator being configured for dampening ink pressure pulses.

12. The printer of claim 11 , wherein said printhead comprises one or more second air accumulators communicating with ink channels in the printhead, said second air accumulators being configured for dampening ink pressure pulses.

13. The printer of claim 12 , wherein said one or more second air accumulators are configured for dampening relatively high frequency pressure pulses and said first air accumulator is configured for dampening relatively low frequency pressure pulses.

14. The printer of claim 13 , wherein said first air accumulator has a larger volume than each of said one or more second air accumulators.

15. The printer of claim 1 , wherein said printhead is removably replaceable in said printer.

16. The printer of claim 15 , wherein said printhead comprises an inlet coupling and an outlet coupling, said inlet coupling being detachably connected to a complementary upstream ink line coupling and said outlet coupling being detachably connected to a complementary downstream ink line coupling.