{"id":1631,"date":"2026-09-16T17:00:00","date_gmt":"2026-09-16T09:00:00","guid":{"rendered":"https:\/\/borrapumps.com\/blog\/jockey-pump-sizing\/"},"modified":"2026-09-15T14:33:40","modified_gmt":"2026-09-15T06:33:40","slug":"jockey-pump-sizing","status":"publish","type":"post","link":"https:\/\/borrapumps.com\/de\/blog\/jockey-pump-sizing\/","title":{"rendered":"How to Size a Jockey Pump for a Fire Protection System"},"content":{"rendered":"

Size a jockey pump to replace normal system leakage and small pressure losses without meeting sprinkler or hose demand and without repeatedly starting the main fire pump. Determine realistic leakage, system volume and pressure behavior, required pressure, acceptable run time, and the coordinated start-stop sequence. Select a small pump whose curve can reach the intended stop pressure at low flow, then verify that a genuine fire demand produces enough pressure decay to start the main fire pump. Keep the calculation and acceptance record with the final project documents so future tests use the same basis.<\/p>\n

Safety and scope:<\/strong> Fire pumps and their drivers are life-safety equipment. Hydraulic, electrical, diesel, fuel, battery, pressure, rotating-equipment, testing, and impairment work must follow the current approved design, manufacturer instructions, applicable standards, and the authority having jurisdiction. This guide explains the engineering decision path; it does not authorize field changes, bypasses, or operation by unqualified personnel.<\/p>\n

Contents<\/strong><\/p>\n
    \n
  1. Define the jockey pump's job<\/a><\/li>\n
  2. Estimate normal leakage<\/a><\/li>\n
  3. Understand system volume<\/a><\/li>\n
  4. Set the required pressure range<\/a><\/li>\n
  5. Check the pump curve<\/a><\/li>\n
  6. Limit short cycling<\/a><\/li>\n
  7. Coordinate controls and alarms<\/a><\/li>\n
  8. Commission the sequence<\/a><\/li>\n
  9. Decision table<\/a><\/li>\n
  10. Frequently asked questions<\/a><\/li>\n<\/ol>\n<\/div>\n

    Define the jockey pump's job<\/h2>\n

    It maintains normal system pressure after small losses. It is not a substitute for the main fire pump and should not mask material leakage. Treat this as a system condition rather than an isolated component choice. Identify the source of every input, the unit used, the operating condition it represents, and the person responsible for approval. If information is preliminary, mark the assumption and test how the decision changes at a conservative boundary. This prevents a neat calculation from hiding an uncertain water level, pressure, valve position, driver condition, or simultaneous demand.<\/p>\n

    For jockey pump sizing, verify this section against the selected pump curve, the actual site arrangement, manufacturer instructions, and the current requirements accepted by the authority having jurisdiction. Check the installed condition as well as the drawing because pipe routes, elevations, supports, controls, and access often change during construction. Record the result in a form that can be repeated during commissioning and later inspection. Do not change a safety-critical setting or isolate fire protection without the approved impairment and restoration process.<\/p>\n

    Estimate normal leakage<\/h2>\n

    Use maintenance history, measured pressure decay, known valve and device leakage, and system condition. Investigate abnormal leakage instead of permanently oversizing the jockey pump. The most useful evidence is measured or approved project data, not a copied rule of thumb. Identify the source of every input, the unit used, the operating condition it represents, and the person responsible for approval. If information is preliminary, mark the assumption and test how the decision changes at a conservative boundary. This prevents a neat calculation from hiding an uncertain water level, pressure, valve position, driver condition, or simultaneous demand.<\/p>\n

    For jockey pump sizing, verify this section against the selected pump curve, the actual site arrangement, manufacturer instructions, and the current requirements accepted by the authority having jurisdiction. Check the installed condition as well as the drawing because pipe routes, elevations, supports, controls, and access often change during construction. Record the result in a form that can be repeated during commissioning and later inspection. Do not change a safety-critical setting or isolate fire protection without the approved impairment and restoration process.<\/p>\n

    Understand system volume<\/h2>\n
    \"How
    Design and installation details to verify for this topic.<\/figcaption><\/figure>\n

    Large networks, tanks, and trapped air affect how quickly pressure changes. System compressibility influences cycling but does not create a universal sizing ratio. Review this condition at normal, test, and credible abnormal states before procurement. Identify the source of every input, the unit used, the operating condition it represents, and the person responsible for approval. If information is preliminary, mark the assumption and test how the decision changes at a conservative boundary. This prevents a neat calculation from hiding an uncertain water level, pressure, valve position, driver condition, or simultaneous demand.<\/p>\n

    For jockey pump sizing, verify this section against the selected pump curve, the actual site arrangement, manufacturer instructions, and the current requirements accepted by the authority having jurisdiction. Check the installed condition as well as the drawing because pipe routes, elevations, supports, controls, and access often change during construction. Record the result in a form that can be repeated during commissioning and later inspection. Do not change a safety-critical setting or isolate fire protection without the approved impairment and restoration process.<\/p>\n

    Set the required pressure range<\/h2>\n

    The jockey pump must reach the approved stop pressure while its start point remains above the main fire pump start point in the coordinated sequence. The design team should turn this point into a traceable calculation or drawing note. Identify the source of every input, the unit used, the operating condition it represents, and the person responsible for approval. If information is preliminary, mark the assumption and test how the decision changes at a conservative boundary. This prevents a neat calculation from hiding an uncertain water level, pressure, valve position, driver condition, or simultaneous demand.<\/p>\n

    For jockey pump sizing, verify this section against the selected pump curve, the actual site arrangement, manufacturer instructions, and the current requirements accepted by the authority having jurisdiction. Check the installed condition as well as the drawing because pipe routes, elevations, supports, controls, and access often change during construction. Record the result in a form that can be repeated during commissioning and later inspection. Do not change a safety-critical setting or isolate fire protection without the approved impairment and restoration process.<\/p>\n

    Practical decision table<\/h2>\n
    \n\n\n\n\n\n\n\n\n\n\n
    Sizing input<\/th>\nEffect on jockey pump<\/th>\nHow to verify<\/th>\n<\/tr>\n<\/thead>\n
    Normal leakage<\/td>\nSets required makeup flow<\/td>\nPressure-decay test and history<\/td>\n<\/tr>\n
    System volume<\/td>\nAffects pressure-change rate<\/td>\nDrawings and field behavior<\/td>\n<\/tr>\n
    Target pressure<\/td>\nSets required head<\/td>\nApproved pressure sequence<\/td>\n<\/tr>\n
    Pump curve<\/td>\nShows low-flow head capability<\/td>\nManufacturer curve<\/td>\n<\/tr>\n
    Check valves<\/td>\nLeakage can cause cycling<\/td>\nIsolation and leak checks<\/td>\n<\/tr>\n
    Sensing line<\/td>\nControls measured pressure<\/td>\nField route and valve position<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

    Check the pump curve<\/h2>\n

    Select against low-flow, high-head operation. Confirm minimum stable operation, shutoff head, motor load, and manufacturer limitations. Treat this as a system condition rather than an isolated component choice. Identify the source of every input, the unit used, the operating condition it represents, and the person responsible for approval. If information is preliminary, mark the assumption and test how the decision changes at a conservative boundary. This prevents a neat calculation from hiding an uncertain water level, pressure, valve position, driver condition, or simultaneous demand.<\/p>\n

    For jockey pump sizing, verify this section against the selected pump curve, the actual site arrangement, manufacturer instructions, and the current requirements accepted by the authority having jurisdiction. Check the installed condition as well as the drawing because pipe routes, elevations, supports, controls, and access often change during construction. Record the result in a form that can be repeated during commissioning and later inspection. Do not change a safety-critical setting or isolate fire protection without the approved impairment and restoration process.<\/p>\n

    Limit short cycling<\/h2>\n
    \"How
    Inspection and commissioning details to document before handover.<\/figcaption><\/figure>\n

    Review check-valve leakage, pressure-tank function where used, sensing line location, system volume, and the gap between start and stop settings. The most useful evidence is measured or approved project data, not a copied rule of thumb. Identify the source of every input, the unit used, the operating condition it represents, and the person responsible for approval. If information is preliminary, mark the assumption and test how the decision changes at a conservative boundary. This prevents a neat calculation from hiding an uncertain water level, pressure, valve position, driver condition, or simultaneous demand.<\/p>\n

    For jockey pump sizing, verify this section against the selected pump curve, the actual site arrangement, manufacturer instructions, and the current requirements accepted by the authority having jurisdiction. Check the installed condition as well as the drawing because pipe routes, elevations, supports, controls, and access often change during construction. Record the result in a form that can be repeated during commissioning and later inspection. Do not change a safety-critical setting or isolate fire protection without the approved impairment and restoration process.<\/p>\n

    Coordinate controls and alarms<\/h2>\n

    Keep the sensing line independent and correctly arranged, protect it from blockage or trapped air, and document controller modes and alarm response. Review this condition at normal, test, and credible abnormal states before procurement. Identify the source of every input, the unit used, the operating condition it represents, and the person responsible for approval. If information is preliminary, mark the assumption and test how the decision changes at a conservative boundary. This prevents a neat calculation from hiding an uncertain water level, pressure, valve position, driver condition, or simultaneous demand.<\/p>\n

    For jockey pump sizing, verify this section against the selected pump curve, the actual site arrangement, manufacturer instructions, and the current requirements accepted by the authority having jurisdiction. Check the installed condition as well as the drawing because pipe routes, elevations, supports, controls, and access often change during construction. Record the result in a form that can be repeated during commissioning and later inspection. Do not change a safety-critical setting or isolate fire protection without the approved impairment and restoration process.<\/p>\n

    Commission the sequence<\/h2>\n

    Create a controlled small pressure loss, verify jockey start and stop, then create the approved larger demand and verify main pump start without delay. The design team should turn this point into a traceable calculation or drawing note. Identify the source of every input, the unit used, the operating condition it represents, and the person responsible for approval. If information is preliminary, mark the assumption and test how the decision changes at a conservative boundary. This prevents a neat calculation from hiding an uncertain water level, pressure, valve position, driver condition, or simultaneous demand.<\/p>\n

    For jockey pump sizing, verify this section against the selected pump curve, the actual site arrangement, manufacturer instructions, and the current requirements accepted by the authority having jurisdiction. Check the installed condition as well as the drawing because pipe routes, elevations, supports, controls, and access often change during construction. Record the result in a form that can be repeated during commissioning and later inspection. Do not change a safety-critical setting or isolate fire protection without the approved impairment and restoration process.<\/p>\n

    How this relates to BORRAPUMP equipment<\/h2>\n

    BORRAPUMP supplies engineered pump equipment for water and fire-protection projects. Review the relevant BORRAPUMP product configuration<\/a> as a starting point, then submit the required flow, head, water source, driver, power, controls, site conditions, applicable requirements, quantity, and destination. Final selection must use the project hydraulic basis and approved submittal; this guide does not claim that one catalog arrangement fits every jurisdiction or risk.<\/p>\n

    Related BORRAPUMP guides<\/h2>\n