Water bath control temperature range from ambient +5? to 99.9?, with large volume of internal and external circulation pump Internal circulation pump enables precise temperature uniformity in the bath within ± 0.3? comparing to conventional heated water bath without circulation system. External circulation pump enables to circulates water (liquid) to external equipments which needs to be kept constant temperature. External circulation flow rate is 7 ~ 20 liters/minute and pressure is 450 mbar.