Pump curve
System & pumps
Awaiting Valid Duty Parameters
Adjust the parameters on the left to compute live hydraulic values, ranges, and sizing verdicts.
Planning a second pump?
Adding a pump the wrong way costs money and downtime. Our engineers model your system curve and recommend the right arrangement.
Series vs parallel, without the guesswork
The rule in one line
Parallel pumps add flow at the same head; series pumps add head at the same flow. The operating point, however, depends on the system curve — and that is where most mistakes happen. On a system with high static head, parallel pumps gain little because each pump must still climb the same static head; series pumps push through it. On a low-static, friction-heavy system, parallel wins.
The analyzer builds the combined curves and solves each against your system curve, so the recommendation comes from your numbers, not from a rule of thumb.
Pump fighting and overload
Parallel pumps fight when the system curve is steep (high static head) and the pump curve is flat: one pump can run far out on its curve while the other throttles back or deadheads. Series pumps overload when the second pump sees the full combined head at low flow — the motor current climbs even though the pump seems to do nothing.
The analyzer flags both patterns. If the parallel gain is under ~10 %, it warns that parallel operation is marginal. If series head approaches double the single head at the operating point, it warns to check the second pump.
When each makes sense
Parallel suits variable demand: two pumps, one duty one standby, or both running for peak flow. Series suits fixed high-head duties — boiler feed, high-rise boosting, long pipelines. A third option for variable flow is one pump with a VFD, which often beats both arrangements on energy — the affinity calculator shows the saving. Teflow’s engineers model multi-pump stations for chemical and water plants — call +91 98251 62709.
Technical & Operational FAQs
Q1.Do pumps in parallel double the flow?
Only on a friction-dominated system with low static head. Each parallel pump delivers roughly its own curve flow, but the system demands more head as flow rises, so the total gain is usually 60–90 % of double, and much less when static head is high. The analyzer computes the real operating point.
Q2.When are pumps connected in series?
Series connection adds the heads of the pumps at the same flow — used for high-static-head duties such as boiler feed, high-rise boosting and long transfer lines. The second pump must be rated for the combined discharge head.
Q3.What is pump fighting?
In parallel, pumps fight when one operates far from its best efficiency point while the other compensates — typically on steep system curves with flat pump curves. Symptoms: vibration, surging flow, one pump drawing most of the current. The analyzer warns when parallel gain is marginal.
Q4.Can different-size pumps run in parallel?
They can, but the smaller pump should be selected so its shutoff head is close to the larger one; otherwise the smaller pump can deadhead at low demand. This tool assumes identical pumps — for mixed sizes, model each combination on its curve and confirm with the manufacturer.
Q5.Series or parallel for a boiler feed?
Boiler feed needs head, not flow: series (or a multistage pump) is the right shape. Parallel pairs suit variable water demand where each pump can handle base load. Enter your system numbers in the analyzer to see which crosses your curve higher.
Related Engineering Tools
System Curve Tool
Chemical Pump Sizing Calculator
Affinity Laws Calculator
Pipe Head Loss Calculator
Pump Consultancy
Centrifugal Chemical Pumps
Need a custom hydraulic audit or specific duty curve verification? Call +91 98251 62709 or Request a Detailed Engineering Quote.